CICS (Customer Information Control System)

1
CICS(Customer Information Control System)
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Table of Contents

• Introduction to CICS
• Basic Mapping Support
• Program Control
• File Processing
• Error Handling
• Queues
• Interval and Task Control
• Recovery and Restart
• Program preparation
• CICS Supplied Transactions
• Case Study

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Introduction to CICS

• Customer Information Control System -CICS
  developed in late 1960s as a DB/DC control
  system
• CICS provides an interface between the Operating
  System and application programs
• Macro Level CICS - initial version Assembler
  macro to request CICS services
• Command Level CICS - high level lang.version -
  commands to request CICS services - Single
  command can replace series of macros

4
Batch Online Differences

• BATCH SYSTEM
• Input data is prepared and given in sequence
  (file)
• Processing sequence is predictable and hence
  restarting the process in case of failure is
  easy.
• Programs and files cant be shared
• Programs are scheduled through jobs
• O/P printed on paper or in sequential of VSAM or
  Indexed files
• Response time Could be scheduled to be Hours or
  days

• ONLINE SYSTEM
• Data is entered as needed not in sequence
  (terminal)
• Since processing sequence is unpredictable,
  special recovery/restart proc. is required in
  case of failure
• Programs and files can be shared
• Transaction can be run at any time
• O/p displayed on Terminal updated files
• Response Time Could be in minutes or second.
  Usually in seconds

5
CICS Operating System
Operating System
CICS
Enter Code
Users App.
Files Database
6
DB/DC System
Terminals
Data Base
Central System
CICS System Environment API routines, and
Application Programs
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CICS System Services

• Data-Communication Functions
• Data-Handling Functions
• Application Program Services
• System Services
• Monitoring Functions

8
Task Transaction

• Task - A basic unit of work which is scheduled
  by the
• operating system or CICS
• Ex -Read from and write to the terminal
• Transaction - An entity which initiates
  execution of a task. In CICS, transaction is
  identified by the transaction identifier
  (Trans-id)

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Application Programming Concepts

• Pseudo-Conversational
• Multitasking
• Multithreading
• Quasi-Reentrancy

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Terminal Conversation

• Conversational A mode of dialogue between
  program and terminal based on a combination of
  sending message and receiving message within the
  same task
• Since human response is slower than the CPU
  speed, a significant amount of resource will be
  wasted just waiting
• Pseudo-Conversational. A mode of dialogue between
  program and terminal which appears to the
  operator as a continuous conversation but which
  is actually carried by a series of tasks

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Terminal Conversation Example

• PROCEDURE DIVISION.
• FIRST-PROCESS.
• EXEC CICS RECEIVE ---- lt TSK1,12345
• END-EXEC.
• process
• EXEC CICS SEND ----- lt EMP(12345)
  Details
• END-EXEC.
• - - - - - - Program Waits For
  Response - - - - -
• SECOND PROCESS.
• EXEC CICS RECEIVE ----- lt User Enters
  Data
• END-EXEC.
• process

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Pseudo-Conversation Example
Transaction TSK2 Program PROG2 PROCEDURE
DIVISION. EXEC CICS RECEIVE
END-EXEC. EXEC CICS SEND
END-EXEC. EXEC CICS RETURN END-EXEC.

• Transaction TSK1
• Program PROG1
• PROCEDURE DIVISION.
• EXEC CICS RECEIVE
• END-EXEC.
• EXEC CICS SEND
• END-EXEC.
• EXEC CICS RETURN
• TRANSID (TSK2)
• END-EXEC.

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CICS Components

• Control Programs (or Management Modules)
• Programs that interface between OS and app. pgm
• Handle the general functions that are crucial to
  operation of
• CICS
• Control Tables
• Define the CICS environment
• Functionally associated with the management
  module
• Control Blocks (or Areas)
• Contain system type information. Eg. Task Control
  Area
• contains information about the task

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Mangement Pgms Ctrl Tables

• Programs
• Program Control PCP
• File control FCP
• Terminal Control TCP
• Task Control KCP
• Temporary Storage TSP
• Transient Data TDP
• Storage Control SCP
• Interval Control ICP
• Journal Control JCP

• Tables
• Processing Program
• Table PPT
• File Control Table FCT
• Terminal Control Table TCT
• Program Control Table PCT
• Temp. Storage Table TST
• Destin. Control Table DCT

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CICS Program Considerations

• Considerations
• Must eventually return control to CICS
• Cant modify procedure division instructions
  because CICS programs may be shared by many tasks
• Can modify working storage since a unique copy of
  working storage is created for each task

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CICS Program Restrictions

• Restrictions
• No CONFIG. SECTION, I/O SECTION to be specified
  in the ENVIRONMENT DIVISION.
• FILE SECTION, OPEN, CLOSE, and non-CICS READ
  WRITE statements are not permitted because file
  management is handled by CICS.
• COBOL commands such as ACCEPT, DISPLAY, EXHIBIT,
  TRACE, STOP RUN, GOBACK are avoided. (STOP RUN
  GOBACK are sometimes included in order to
  eliminate compiler diagnostic but never executed)

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Sample CICS Program

• IDENTIFICATION DIVISION.
• PROGRAM-ID. SAMPLE.
• ENVIRONMENT DIVISION.
• DATA DIVISION.
• WORKING-STORAGE SECTION.
• 01 WS-INPUT.
• 05 WS-TRANSID PIC X(4).
• 05 FILLER PIC X(1).
• 05 WS-IN-EMP-CD PIC X(4) VALUE ALL X.

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Sample Program (Contd..)

• 01 WS-OUTPUT.
• 05 FILLER PIC X(16) VALUE EMP
  CODE .
• 05 WS-OUT-EMP-CD PIC X(4).
• 01 WS-LENGTH PIC S9(4) COMP.
• LINKAGE SECTION.
• CAN Include DFHCOMMAREA if data needs to be
  communicated between two transactions or
  multiple iterations of the same transaction.
• PROCEDURE DIVISION.
• 000-MAINLINE.
• PERFORM 100-RECV-INPUT.
• PERFORM 200-SEND-OUTPUT.
• EXEC CICS RETURN END-EXEC.

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Sample Program (Contd..)

• 100-RECV-INPUT.
• MOVE 9 TO WS-LENGTH.
• EXEC CICS RECEIVE
• INTO (WS-INPUT) LENGTH
  (WS-LENGTH)
• END-EXEC.
• MOVE WS-IN-EMP-CODE TO
  WS-OUT-EMP-CODE
• 200-SEND-OUTPUT.
• EXEC CICS SEND
• FROM (WS-OUTPUT) LENGTH
  (20) ERASE
• END-EXEC.

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CICS Translator

• The CICS translator converts CICS commands
  into the COBOL code so that it could be compiled
  by a Standard Cobol compiler

CICS Translator
COBOL Statements
CICS program with CICS Commands
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Translator

• When you compile a CICS/VS program the translator
  will automatically add many lines of code to your
  program, which can be seen in the compiled
  listing

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Basic Mapping Support

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Topics in BMS

• Introduction to BMS
• Map and Mapset
• Physical and Symbolic Map
• Map Definition Macros
• Screen Manipulation/Handling
• Screen Design Considerations
• Interfacing with Terminal using a Map

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Introduction to BMS

• Introductory concepts
• In online systems, formatted screens are used.
  In order to display formatted screen, a terminal
  (e.g. 3278) must receive a series of data stream
  called Native Mode Data Stream (NMDS) based on
  the hardware protocol this NMDS is a mixture of
  Buffer Control Characters (BCCs) and text data.
  NMDS is designed for a particular terminal and is
  thus both device dependent and format dependent.
  So if NMDS is used, re-coding is required
  whenever there is change in the terminal device
  or screen format. To remove this device and
  format dependency from application program, CICS
  provides a facility called Basic Mapping Support
  (BMS).

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Primary Functions of BMS

• Removal of device dependent codes from
  Application Program
• Removal of constant information from Application
  program (Headers, Titles...)
• Construct NMDS - Native Mode Data Stream
• Text handling
• Terminal Paging Message routing
• Contents of the screen defined thru BMS is
  called Map.
• Map is a program written in assembly language.
• BMS macros are available for Map coding.
• The BMS Macros are coded in the form of Maps,
  and Mapsets to define the screen attributes,
  screen field positions, and field
  characteristics.

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Map and Mapset

• Representation of one screen format is called
  Map (screen panel).
• One or more maps, link edited together, makes up
  a Mapset (load module).
• Mapset must have a entry in PPT as given below
• DFHPPT TYPEENTRY,MAPSETname
• Or DFHPPT TYPEENTRY,PROGRAMname

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Map and Mapset (Contd..)

• Mapset name has two parts.
• Generic name 1- 7 chars. Used in App. Program.
• Suffix 1 char. To identify the device
  type
• Multimap Panel
• Dynamically constructing a screen panel with
  multiple maps at the execution time

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Map and Mapset (Contd..)

• The concepts of map and mapset can be utilized
  in two type of cases as given below
•  Case 1 A mapset consist of a single map. For
  e.g.
• MAPSET1 MAPNUM1
•  Case 2 A mapset consists of several maps. For
  e.g.
• MAPSET2 MAPNUM1
• MAPNUM2

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Types of MAPS

• There are 2 types of MAPS
• Physical Map
• Physical Map is a map used by CICS (CSECT)
• Ensure device independence in the application
  program
• BMS macro coding gt Assemblygt Link edit gt
  Load module gt LOADLIB gt To be used by CICS
• Symbolic Map
• Ensure device and format independence in the
  application program
• Symbolic Map is a map used by Application Program
  (DSECT)
• BMS macro coding gt Assembly gt Symbolic map
  definition gt COPYLIB gt Copied (COPY) into
  CICS application program.

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Example Symbolic Map

• 01 EMPRECI.
• 02 FILLER PIC X(12).
• 02 EMPNAL PIC S9(4) COMP.
• 02 EMPNAF PIC X.
• 02 FILLER REDEFINES EMPNAF.
• 03 EMPNAA PIC X.
• 02 EMPNAI PIC X(21).
• 01 EMPRECO REDEFINES EMPRECI.
• 02 FILLER PIC X(12).
• 02 FILLER PIC X(03).
• 02 EMPNAO PIC X(21).

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Physical Symbolic Map - Logic Flow
BMS source
Assembler
Physical MAP
Linkage editor
Symbolic MAP
Load module (MVS)
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Physical Map

• Physical Map.
• The BMS macros are assembled and link-edited into
  CICS load library to create the physical map. The
  mapset like any other CICS program is stored in
  CICS runtime library the PPT(Program Processing
  Table). At the program execution time the
  physical map is being used by CICS to load the
  screen image.
• In case of input operations, the physical map
  defines the maximum length, the starting position
  for each field to be read and allows BMS to
  interpret an input NMDS.
• In case of output operations, the physical map
  defines the starting position, length, field
  characteristics and the default data for each
  field and allows BMS to construct an output NMDS.

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Symbolic Map

• The symbolic map is coded using the BMS macro,
  assembled separately and catalogued into a copy
  library. The symbolic map serves as a DSECT for
  referencing the Terminal Input/Output Area
  (TIOA). The program issues a COBOL COPY statement
  to include it in the program.
• The symbolic maps represents the actual data
  structure of the fields defined in the physical
  map, and is used by the application program to
  send and receive information from the terminal,
  in the CICS SEND-MAP RECEIVE MAP commands.
• The symbolic map can be used by the CICS
  application programs to dynamically to alter the
  field attributes, modify screen cursor position,
  and highlight , protect , unprotect specific
  fields on the screen.

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Map definition Macros

• General Format
• Column Number
• 1 16 72
• setname operation operands contd.
• Example
• EMPMAP DFHMSD TYPEMAP, X
• MODEINOUT, X
• LANGCOBOL, X
• STORAGEAUTO, X
• TIOAPFXYES
• ANY COMMENTS

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Map definition Macros (Contd..)

• Explanations
• SETNAME Name of the mapset. Used in CICS
  command to read or write one of the maps in
  the mapset. It is the load module name.
• OPERATION Macro identifier. Mapset/Map/Field
  definition.
• OPERANDS Optional key words (parameters)
  separated by comma.
• CONTD Current line can be continued by leaving
  this column non-blank (usually X) and the
  next line have to be started in 16th column.
• Comments in column 1 makes the line comment.

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Map definition Macros (Contd..)

• INITIAL VALUES Always surround initial values
  by single quote marks
• Escape Chars and

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Order of Macros

• DFHMSD TYPEDSECT Mapset
• DFHMDI Map
• DFHMDF A field
• DFHMDF A field
• DFHMDI Map
• DFHMDF A field
• DFHMDF A field
• 
  
• DFHMSD TYPEFINAL Mapset
• END

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DFHMSD Macro

• The DFHMSD macro is used to define a mapset
  (TYPEMAP) and its characteristics or to end a
  mapset definition (TYPEFINAL). Only one mapset
  is allowed in one assembly run. All the maps in a
  map set get assembled together, and they're
  loaded together at execution time.
• Example
• TSTMSET DFHMSD TYPESYSPARM, X
  MODEINOUT, X LANGCOBOL, X STORA
  GEAUTO, X TIOAPFXYES, X CNTL(FREEKB,
  FRSET,PRINT)

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DFHMSD Macro (Contd..)

• Options
•  
• TYPE To define the map type
• DSECT For symbolic map
• MAP For physical map
• SYSPARM For special assembly procedure
• FINAL To indicate the end of a mapset coding
•  
• MODE To indicate input/output operations
• IN For an input map only
• OUT For an output map only
• INOUT For maps involving both input and output.

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DFHMSD Macro (Contd..)

• STORAGE
• AUTO To acquire a separate symbolic map area
  for each mapset
• BASE To have the same storage base for the
  symbolic maps of from more than one mapset
• TIOAPFX
• YES To reserve the prefix space (12 bytes) for
  BMS
• commands to access TIOA properly. Required for
  the CICS command level.

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DFHMSD Macro (Contd..)

• CNTL To define the device control
  requests
• FREEKB To unlock the keyboard
• FRSET To reset MDT to zero status
• ALARM To set an alarm at screen display
  time
• PRINT To indicate the mapset to be sent
  to the printer
• TERMtype This ensures device
  independence, required if other than
  3270 terminal is being used
• SUFFIXnn To specify the user provided
  suffix number. This must correspond to
  the TCT parameter.

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DFHMDI Macro

• Defines a map and its characteristics
• Example
• EMPMAP DFHMDI SIZE(ll,cc), X LINEnn, X
  COLUMNmm, X JUSTIFYLEFT/RIGHT
• Options
• SIZE(ll,cc) To define the size of the map by
  the line size (ll) and the column size (cc).
  Useful when the screen contains.
• LINE Indicates the starting line number of the
  map.
• COLUMN Indicates the starting column number of
  the map.
• JUSTIFY To specify the entire map (map fields)
  is to be left or
• right justified.

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DFHMDF Macro

• The DFHMDF macro is used to define a field in a
  map and its characteristics. This is the position
  on the screen where the field should appear. It's
  the position relative to the beginning of the
  map. Field starts with its attribute byte, so if
  POS(1,1) is coded, then the attribute byte for
  that field is on line 1 in column 1, and the
  actual data starts in column 2. The length of the
  field (not counting the attribute byte) is
  specified. Literals can be specified within
  quotes these character data is for an output
  field. It is used to define labels and titles for
  the screen and keep them independent of the
  program.

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Sample Screen layout

• The above defines the screen layout as given
  below
•  
• Where
• Is the Attribute character
• n Is unprotected numeric
• _ Is Cursor

ITEM NUMBER nnnnnnnn
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DFHMDF Macro For The Above Layout

• Define a field and its characteristics
• Example
• DFHMDF POS(ll,cc), X
• INITIALCustomer No. , X
• ATTRBASKIP, X
• LENGTH14
• CUSTNO DFHMDF POS(ll,cc), X
• ATTRB(UNPROT,NUM,FSET,IC), X
• JUSTIFYRIGHT, X
• PICIN9(8), X
• PICOUT9(8), X
• LENGTH8

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Attribute character

• Function
• The attribute character is an invisible 1-byte
  character, which precedes a screen field and
  determines the characteristics of a field.
• ASKIP Autoskip. Data cannot be entered in this
  field. The cursor skips to the next field.
• PROT Protected field. Data cannot be entered into
  this field. If data is entered, it will cause
  the input-inhibit status.
• UNPROT Unprotected field. Data can be entered and
  this is used for all input fields.
• NUM Numeric field. Only numbers (0 to 9) and
  special characters (. and -) are allowed.

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Attribute character (Contd..)

• BRT Bright display of a field (highlight).
• NORM Normal display.
• DRK Dark display.
• IC Insert cursor. The cursor will be positioned
  in this field. In case, IC is specified more
  than once, the cursor is placed in the last
  field.
• FSET Field set. MDT is set on so that the field
  data is to be sent from the terminal to the host
  computer regardless of whether the field is
  actually modified by the user.

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Modified Data Tag

• Function
• Modified Data Tag (MDT) is a one bit of the
  attribute character. If it is off (0), it
  indicates that the terminal operator has not
  modified the field. If it is on (1), it indicates
  that the operator has modified this field. Only
  when MDT is on, the data of the field will be
  sent by the terminal hardware to the host
  computer. An effective use of MDT drastically
  reduces the amount of data traffic in the
  communication line and thus improves performance.
  
• Three ways of setting and resetting the MDT.  
• 1. Terminal user modifies a field on the
  screen, it is automatically set to 1 (on) by
  the terminal hardware.
•  

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Modified Data Tag (Contd..)

• 2. If CNTLFRSET is specified in the DFHMSD or
  DFHMDI macro, when the mapset or the map is sent
  to the terminal, MDT will be reset to 0 (off)
  i.e. not modified for all the fields of the
  mapset or the map.
•  
• 3. If FSET is specified in the ATTRB parameter
  of the DFHMDF macro for a field, when the map is
  sent to the terminal, MDT will be set to 1.
  (on i.e. modified) for the field regardless of
  whether the field has been modified by the
  terminal user.

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Skipper Technique

• Unlabelled 1-byte field with the autoskip
  attribute
  
• DFHMDF POS(ll,cc),ATTRBASKIP,LENGTH1
• To skip the cursor to the next unprotected field
  after one unprotected field.
• Screen Layout
• xxxxx xx
• where
• Skipper field
• Attribute byte
• X Unprotected field

51
Stopper Technique

• Unlabelled 1-byte field with the protect
  attribute
  
• DFHMDF POS(ll,cc),ATTRBPROT,LENGTH1
• To stop the cursor in order to prevent erroneous
  field overflow by terminal user.
• Screen Layout
• xxxxx
• where
• Stopper field

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Format Of the Symbolic Map

• Format of Symbolic Map
• Once the symbolic map is assembled and is placed
  in the COPY library, the COBOL COPY statement can
  be used to include it in the application program.
  
• The symbolic map starts with the 01 level
  definition of the map name specified in the
  DFHMDI macro with the suffix I for the input
  map and the suffix O for the output map.
• Next is the definition of FILLER PIC X(12), which
  is the TIOA prefix created by the TIOAPFXYES of
  the DFHMSD macro this is required by the BMS
  under the CICS command level.

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Format Of the Symbolic Map (Contd..)

• For each field name (1 to 7 characters)
  specified in the DFHMDF macro, BMS creates three
  fields for inputs and three fields for outputs,
  by placing one character suffix to the original
  field name. The meaning of these fields are given
  below
•  
• Name L The half-word binary (PIC S9(4) COMP)
  field. For the input field, the actual number of
  characters typed in the field will be placed by
  the BMS when the map is received. For the output
  field, this is used for the dynamic cursor
  positioning.

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Format Of the Symbolic Map (Contd..)

• Name F Flag Byte. For the input field, it will
  be X80 if the field has been modified but no
  data is sent (i.e. the field has been cleared).
  Otherwise this field is X00.
• Name A The Attribute byte for both input and
  output fields.
• Name I The input data field. X00 will be
  placed if no data is entered. Note that space
  X40 is data. The application program should
  differentiate X00 from space (X40).
•  
• Name O The output data field.

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Example Of Symbolic Map

• 01 EMPRECI.
• 02 FILLER PIC X(12).
• 02 EMPNAL PIC S9(4) COMP.
• 02 EMPNAF PIC X.
• 02 FILLER REDEFINES EMPNAF.
• 03 EMPNAA PIC X.
• 02 EMPNAI PIC X(21).
• 01 EMPRECO REDEFINES EMPRECI.
• 02 FILLER PIC X(12).
• 02 FILLER PIC X(03).
• 02 EMPNAO PIC X(21).

56
Cursor Positioning Techniques

• CICS provides multiple ways of to specify where
  to position the cursor on the screen. The cursor
  positioning is important to prompt an user of an
  entry he has to make, or to point to an error
  which has occurred during editing the user
  entries.
• Static positioning (Achieved thru Map definition
  ATTRIBIC).
• Example
• DFHMDF POS(5,8),ATTRB(UNPROT,FSET,IC),LENGTH1
  0

57
Cursor Positioning Techniques (Contd..)

• Dynamic/Symbolic Positioning.
• The cursor is placed dynamically through an
  application program by moving -1 to the symbolic
  map field-length field (i.e. fieldname L) for
  the field where the cursor is to be placed. The
  SEND MAP command must be issued with the CURSOR
  option (without value). Also, the mapset should
  be coded with MODEINOUT in the DFHMSD macro.
  This approach is very useful when the cursor is
  to be placed at the field where data entry error
  has been detected by the data edit routine.

58
Cursor Positioning Techniques (Contd..)

• Example Of Dynamic Cursor Positioning.
• WORKING-STORAGE SECTION.
• COPY MAPSET1
• 01 MAPSET1I
• 05 FILLER PIC X(6).
• 05 FIELD1L PIC X(5).
• 05 FIELD1F PIC X.
• 05 FIELD1I PIC X.
•  

59
Cursor Positioning Techniques (Contd..)

• PROCEDURE DIVISION.
• MOVE 1 TO FIELDL.
• EXEC CICS SEND MAP(MAP1)
• MAPSET(MAPSET1)
• CURSOR
• ERASE
• END-EXEC.
• The cursor will be placed at FIELD1 field of the
  map during execution.

60
Cursor Positioning Techniques (Contd..)

• Dynamic/Relative Positioning (application
  program)
• The cursor is placed dynamically through an
  application program using the CURSOR(data-value)
  option in the SEND MAP command with the value of
  the relative position (starting from zero) of the
  terminal. At the completion of the SEND MAP
  command, the map will be displayed with the
  cursor placed at the specified position,
  overriding the static cursor position defined at
  the map definition time.
•    

61
Cursor Positioning Techniques (Contd..)

• Example EXEC CICS SEND
• MAP(MAP1)
• MAPSET(MAPSET1)
• CURSOR(100)
• ERASE
• END-EXEC.
•  
• The cursor will be placed at FIELD1 field of the
  map MAP1 during execution.

62
Interfacing with a Terminal using a Map

• The BMS maps are used in the application
  programs for the actual terminal input/output
  operation. These operations are performed by a
  set of CICS commands for BMS.
•   The following are the three basic functions
  performed by CICS commands 
• Map Sending function using the data in the
  symbolic map, BMS prepares the output NMDS, the
  corresponding physical map, and sends to the
  terminal.
• Map Receiving Function using the input NDMS
  from the terminal, BMS prepares data in the
  symbolic map through the corresponding physical
  map.
• Text Handling Function BMS prepares text
  without using a map and sends to the terminal.

63
Interfacing with a Terminal using a Map (Contd..)

• Flow of Information from 3270 Terminal and the
  Application Program.

Application Program Send Map Command
Symbolic Map
BMS
Output NDMS
Terminal
Data Entry
Physical Map
Application Program Receive Map Command
Symbolic Map
BMS
Input NDMS
Terminal
64
Interfacing with a Terminal using a Map (Contd..)

• The following are the available commands 
• RECEIVE MAP To receive a map 
• SEND MAP To send a map 
• SEND CONTROL To send a control function to the
  terminal
• SEND TEXT To send a text 
• SEND PAGE To send the accumulated text or
  maps as a logical message

65
Receive Map Command

• RECEIVE MAP Command is used to receive input
  from a terminal. At the completion of the
  command, the symbolic map will contain valid data
  from the terminal in the following three fields
  as per each field defined by the DFHMDF macro
•  
• Field name L The length field, which
  contains the actual number of characters,
  typed in the screen field.
• Field name F The Flag Byte which is normally
  X00. It will be X80 if the field has
  been modified but cleared.
• Field name I The actual input data field.
  X00 will be placed if no data is entered.
  

66
Receive Map Command (Contd..)

• Syntax EXEC CICS RECEIVE
• MAP (MAPNAME)
• MAPSET(MAPSETNAME)
• SET(POINTER) INTO(DATANAME)
• LENGTH(MSG-LEN)
• HANDLE NOHANDLE
• RESP()
• END-EXEC.
• Conditions INVREQ, MAPFAIL

67
Receive Map Command (Contd..)

• MAP specified the name of the MAP defined thru
  DFHMDI command , which describes the screen
  details.
• MAPSET specified the name of the MAPSET defined
  thru DFHMSD command which includes the MAP.
• INTO is used to specify the area in the working
  storage section to which the data from the
  terminal is to be placed.
• SET is used when the address pointer is to be
  set to the address of the symbolic map (by CICS)
  so that the application program can directly
  refer to the record without moving the record
  content into the working storage area defined in
  the program.

68
Receive Map Command (Contd..)

• RESP will be used by CICS to place a response
  code at a completion of the command.
• HANDLE is used to transfer control to the
  procedure label specified if the exceptional
  condition specified occurs.
• NOHANDLE will cause no action to be taken for
  any exceptional condition occurring during
  execution of the CICS command.
• Conditions INVMPSZ , INVREQR , LENGERR,
  MAPFAIL
• MAPFAIL is set when the data being mapped has a
  length of zero. It occurs when the following keys
  are pressed in response to the RECEIVE MAP
  command CLEAR or Attention Keys ENTER or PF
  keys without entering data.

69
SEND MAP Command

• The SEND MAP command is used to send formatted
  output to a terminal. Before issuing this
  command, the application program must prepare the
  data in the symbolic map of the map to be sent,
  which has the following three fields per each
  field defined by the DFHMDF macro
• Name L The length field, for which the
  application program need not prepare except when
  used for the dynamic cursor positioning.
• Name A The Attribute byte for output fields.
  Application program will use it for dynamic
  cursor positioning.
• Name O The actual output data field, where
  the application program places the data.

70
SEND MAP Command (Contd..)

• EXEC CICS SEND MAP(MAP1)
• MAPSET(MAPSET1)
• FROM(DATANAME) , DATAONLY MAPONLY,
• CURSOR(VALUE) ,
• FREEKB , ERASE , FRSET ,
• HANDLE NOHANDLE ,
• RESP (DATANAME)
• END-EXEC.
• Conditions INVREQ,LENGERR

71
SEND MAP Command (Contd..)

• MAP specified the name of the MAP defined thru
  DFHMDI command , which describes the screen
  details.
• MAPSET specified the name of the MAPSET defined
  thru DFHMSD command which includes the MAP.
• MAPONLY is used when no data from your program
  is to be merged into the map.
• DATAONLY is used when only the data from the
  program is to be sent to the screen. The
  constants in the map are not sent.

72
SEND MAP Command (Contd..)

• FROM is used to specify the area in the working
  storage section from which the data is to be sent
  to the terminal.

73
AID KEYS

• First time when a transaction is initiated the
  application program throws the screen image on
  the terminal thru SEND MAP command. Once the
  screen appears, the AID (Attention Identifier )
  Keys are being used to send the information back
  from the terminal to CICS to application program.
  CICS application program needs to trap the
  attention identifier keys and process various
  functions related to the AID keys.
• Salient Points
• PF keys, PA keys, ENTER CLEAR key
• EIBAID in the CICS Executive Interface Block
  contains, recently used AID key.

74
AID KEYS (Contd..)

• DFHAID CICS System copybook which stores the
  values of the EIBAID field for the various AID
  keys. Flow User hits AID key Control goes
  to CICS To Application program. EIBAID contains
  information about the last AID key pressed.
  Program compares EIBAID to the DFHAID field and
  performs processing logic as per the AID key
  pressed.
• HANDLE AID establish the routines that are to be
  invoked when the aid is detected by a RECEIVE MAP
  command.
• Syntax EXEC CICS HANDLE AID
• Option (label)
• END-EXEC
• Conditions INVREQ

75
Screen Design Considerations

• Functional Screen Design
• Screen layout should be similar to source where
  terminal users enter data.
• Screen id should be placed at the top right
  corner of a screen. This helps at problem
  determination time.
• Screen title and field descriptions should be
  self-explanatory.
• Instructions should be concise.

76
Screen Design Considerations (Contd..)

• Large fields can be broken into a number of small
  fields. E.g. the field contact information can be
  split into contact numbers, email ids and postal
  address.
• In case of repeated fields or group of fields,
  sequence numbers helps.
• Error messages should be provided. Preferably the
  last few lines can be used for the error
  messages.

77
Screen Design Considerations

• User-Friendly Screen Design
• Screens should be simple and friendly.
• Default values in fields helps in reducing
  keystrokes by the users. Also, in case the user
  forgets to enter a field data, defaults values
  are assigned according to the field.
• Calculations should be done by program and not by
  users.
• The cursors should be placed in the appropriate
  fields.
• Highlight the error field. Using a different
  colour or blinking the error field can achieve
  this. This enables users to identify the
  erroneous field easily.

78
Screen Design Considerations (Contd..)

• Alarm sound can be used for error entries.
• Provide suitable help messages for erroneous
  entries. The help message should be instructive
  and kind and should not be rude.
• Provide help on fields and their meanings. Using
  an attention key for a help menu, which has
  details on each field, makes a screen
  user-friendly.
• Artistic Screen Design
• A simple screen layout is always preferred.
• Proper use of indentations, spaces, and lines
  makes a screen look good.

79
Screen Design Considerations (Contd..)

• Colour can help in improving the screen design
  however the colour used should be in accordance
  with the norms and standards followed.
• Considerations for Human Errors
• Important and useful fields can be placed at the
  top part of the screen.
• Related fields can be grouped together.
• Protected fields should be skipped automatically.
  This reduces manual skipping and is preferred.
• Skipper/Stopper techniques can be used at
  appropriate places.

80
Exercise - 1
81
CICS File Processing Techniques

82
CICS VS FILE PROCESSING

• File handling in CICS is achieved thru a set of
  file handling commands. It is essential to know
  the various file handling commands for
  application programming.
• File Specific functions to be performed are the
  following.
• Defining a specific file to the CICS system.
• Reading a file sequentially
• Reading a Key Sequenced file randomly
• Reading a file sequentially starting from a
  specific point.
• Reading and Updating a record
• Deleting a Record.
• Handle any errors that occur during file
  processing

83
CICS VS FILE PROCESSING
Instead, CICS has a list of all the files it is
allowed To access. This list is called the FILE
CONTROL TABLE (FCT) and is maintained by the
systems programmers When CICS/VS is started up.
It goes through the FCT and makes all the files
available. When CICS/VS is closed down it closes
all the files.

Files do not need to exclusively defined in
Application programs. The files do not need to
opened and closed in a CICS application program ,
before being used in the program.
Application programs do not need The FD Section,
and the Input Output Section. Application
program directly Refer to filenames in EXEC CICS
Command.
84
CICS COBOL V/S COBOL
BATCH COBOL
CICS COBOL
READ DATAFILE INTO REC-AREA
EXEC CICS READ DATASET (FILE IDENTIFIER) INTO
(RECORD NAME) RID-FLD (record-key) END-EXEC.
AT END MOVE Y TO EOF-FLAG
Replaced by
EXEC CICS WRITE DATASET (File identifier)
FROM (Record-Name) RID-FLD (Record-
key) END-EXEC.
WRITE RECORD-NAME FROM RECORD-AREA
Replaced by
85
VSAM

• Different types of VSAM Datasets used in CICS
  are
• ESDS Entry Sequenced Dataset
• KSDS Key Sequenced Dataset
• RRDS Relative Record Dataset

86
Services Provided By CICS

• Basic Operations required for a file are
• Adding a Record.
• Modifying an Existing Record.
• Deleting an Existing Record.
• Browsing One or Selected or All Records.
• In Addition, CICS Provides
• Exclusive Control. (Record Level Locking).
• Data Independence.
• Journaling.
• Opening and closing Files.

87
Defining Files

• In CICS, files cannot be created. Files can be
  created using IDCAMS Utility.
• Re-indexing, Creating new indexes, etc. should be
  done using IDCAMS Only.

88
Defining A File in CICS

• Files should be defined in FCT (File Control
  Table).
• FCT will contain all the Information about a file
  (like dataset name, access methods, permissible
  file service request, etc.)
• Defining files can be done either by CEDA
  Transaction or DFHFCT Macro.

89
Syntax of DFHFCT Macro

• DFHFCT TYPEFILE,ACCMETHVSAM,
  
• DATASETNAMENAME,
  
• SERVRQ(ADD,BROWSE,DELETE,READ,UPDATE),
• FILSTAT(ENABLED,OPENED)

90
File Handling in Programs

• Files should not be defined in the Program.
• Program should not open or close a File.
• Records can be written in any order. A number of
  records can be added at a time.
• Records can be inserted, updated or deleted.

91
Important Key-Words

• Dataset/File - Name in the FCT.
• Into/From (WS-Rec) - Working-Storage Area
  defined in the program where the CICS Puts/Gets
  the Data.
• RIDFLD - Contains the Record Key.
• RESP - Contains the return code of the
  executed command.
• LENGTH - Length of the Record to be Retrieved
  or Written.

92
Random READ

• EXEC CICS READ File(filename)
  
• SET() Into()
• RIdfld(Rec-Key)
• END-EXEC.
• Condition DISABLED, NOTOPEN, NOTFND, LENGERR,
  DUPKEY, IOERR.

93
Example for Random Read

• EXEC CICS READ
• File( 'INVMAS ')
• Into(WS-INVMAS-REC)
• Length(WS-INVMAS-LEN)
• RIdfld('7135950602')
  RIdfld(WS-INVMAS-KEY)
• END-EXEC.

94
Sequential Read

• Sequential Read is done by Browse Oper.
• Establish the pointer to the First Record to be
  Read Using StartBr.
• Next and Previous Records can be Read as required
  Using ReadNext and ReadPrev.
• End the Browse Operation at last.
• Browse can be re-positioned.
• During Browse Operation, Records cannot be
  Updated.

95
Syntax for STARTBR

• EXEC CICS STARTBR
• FILE(filename)
• RIDFLD(data-area)
• END-EXEC.
• Condition DISABLED, IOERR, NOTFND, NOTOPEN.

96
Reading the Record after STARTBR

• Sequentially the Next or Previous Record can be
  read by a READNEXT or READPREV.
• The first READNEXT or READPREV will read the
  Record where the STARTBR has positioned the File
  Pointer.

97
Syntax of READNext/READPrev

• EXEC CICS READNext READPrev
• FILE(name)
• INTO(data-area)SET(ptr-ref)
• RIDFLD(data-area)
• END-EXEC.
• Condition DUPKEY, ENDFILE, IOERR, LENGERR,
  NOTFND.

98
ENDBRowse

• ENDBRowse terminates a Previously issued STARTBR.
• SYNTAX
• EXEC CICS ENDBR
• FILE(filename)
• END-EXEC.
• Condition INVREQ

99
RESETBR

• Its effect is the same as ENDBR and then giving
  another STARTBR.
• Syntax
• EXEC CICS RESETBR
• FILE(filename)
• RIDFLD(data-area)
• END-EXEC.
• Condition IOERR, NOTFND.

100
WRITE Command

• Adds a new record into the File.
• For ESDS, RIDFLD is not used but after write
  execution, RBA value is returned and Record will
  be written at the end of the File.
• For KSDS, RIDFLD should be the Record Key. The
  record will be written depending on the Key.
• MASSINSERTion must be done in ascending order of
  the Key.

101
Syntax for WRITE

• EXEC CICS WRITE
• FILE(filename)
• FROM(data-area)
• RIDFLD(data-area)
• END-EXEC.
• Condition DISABLED, DUPREC, IOERR, LENGERR,
  NOSPACE, NOTOPEN.

102
REWRITE Command

• Updates a Record which is Previously Read with
  UPDATE Option.
• REWRITE automatically UNLOCKs the Record after
  execution.

103
Syntax for REWRITE

• EXEC CICS REWRITE
• FILE(filename)
• FROM(data-area)
• END-EXEC.
• Condition DUPREC, IOERR, LENGERR, NOSPACE.

104
DELETE Command

• Deletes a Record from a dataset.
• Record can be deleted in two ways,
• 1. RIDFLD with the full key in it
• 2. The record read with READ with UPDATE will be
  deleted.
• Multiple Records Delete is possible using Generic
  Option.

105
Syntax of DELETE

• EXEC CICS DELETE
• FILE(filename)
• RIDFLD(data-area)
  Optional
• END-EXEC.
• Condition DISABLED, DUPKEY, IOERR, NOTFND,
• NOTOPEN.

106
UNLOCK

• To Release the Record which has been locked by
  READ with UPDATE Command.
• Syntax
• EXEC CICS UNLOCK
• FILE(filename)
• other options
• END-EXEC.
• Condition DISABLED, IOERR, NOTOPEN.

107
General Exceptions

• The following exceptions usually will occur for
  ALL CICS file handling commands.
• FILENOTFOUND,
• NOTAUTH,
• SYSIDERR,
• INVREQ

108
CICS Error Handling Procedures

109
Error Handling in CICS

• Possible Errors
• Conditions that aren't normal from CICS's point
  of view but that are expected in the program.
• Conditions caused by user errors and input data
  errors.
• Conditions caused by omissions or errors in the
  application code.
• Errors caused by mismatches between applications
  and CICS tables, generation parameters and JCL
• Errors related to hardware or other system
  conditions beyond the control of an application
  program.

110
Error Handling methods

• When the error (exceptional conditions) occur,
  the program can do any of the following
• Take no action let the program continue -
  Control returns to the next inst. following the
  command that has failed to execute. A return code
  is set in EIBRESP and EIBRCODE. This state
  occurs cause of NO HANDLE /RESP/IGNORE
  conditions
• Pass control to a specified label - Control goes
  to a label in the program defined earlier by a
  HANDLE CONDITION command.
• Rely on the system default action - System will
  terminate or suspend the task depends on the
  exceptional condition occurred

111
Error Handling methods (Contd..)

• HANDLE CONDITION condition(label)...
  'condition' specifies the name of the condition,
  and 'label' specifies the location within the
  program to be branched
• Remains active while the program is executing or
  until it encounters IGNORE/another HANDLE
  condition.
• Syntax
• EXEC CICS HANDLE CONDITION
• ERROR(ERRHANDL)
• LENGERR(LENGRTN)
• END-EXEC
• This example handles DUPREC condition
  separately, all the other Errors together.
  LENGERR will be handled by system

112
HANDLE Condition

• Example of Handle condition
• EXEC CICS HANDLE CONDITION
• NOTFND(RECORD-NOT-FOUND)
• END-EXEC

This condition catches the NOTFND condition and
transfers control to the REC-NOT- FOUND
paragraph in the program. The error handling
logic can be coded in the REC-NOT-FND paragraph.
113
Alternative to Handle condition

• NOHANDLE to specify no action to be taken for
  any condition or attention identifier (AID)
• RESP(xxx) "xxx" is a user-defined full word
  binary data area. On return from the command, it
  contains a return code. Later, it can be tested
  by means of DFHRESP as follows,
• If xxxDFHRESP(NOSPACE) ... or
• If xxxDFHRESP(NORMAL) ...

114
IGNORE Condition

• IGNORE CONDITION condition ...
• condition specifies the name of the condition
  that is to be ignored( no action will be taken)
• Syntax
• EXEC CICS IGNORE CONDITION
• ITEMERR
• LENGERR
• END-EXEC
• This command will not take any actions if the
  given two error occurs and will pass the control
  to the next instruction

115
Sample program to use Handle condition

• Here is an example of the CICS- COBOL code with
  proper handling of errors
• Procedure Division.
• EXEC CICS HANDLE CONDITION
• NOT-FND(REC-NOT-FOUND)
• END EXEC.
• EXEC CICS READ
• DATASET(SAMPLE)
• RIDFLD(EMP-NO)
• INTO (EMP-REC)
• END-EXEC
• GO TO LAST-PART

116
Sample program to use Handle condition (Contd..)

• REC-NOT-FOUND
• MOVE NOT-ON-FILE TO NAMEO ( SYMBOLIC
  MAP
• PARAMETER)
• LAST-PART.
• EXEC CICS SEND
• MAP (TC0BM31)
• MAPSET(TC0BM30)
• FROM (TC0BM310)
• DATA-ONLY
• END-EXEC

117
PUSH POP

• To suspend all current HANDLE CONDITION, IGNORE
  CONDITION, HANDLE AID and HANDLE ABEND commands.
• Used for eg. while calling sub-pgms (CALL).
• While receiving the control, a sub-program can
  suspend Handle commands of the called program
  using PUSH HANDLE.
• While returning the control, it can restore the
  Handle command using POP HANDLE.

118
Syntax of Push Pop

• Syntax of Push
• EXEC CICS Push
• Handle
• END-EXEC.
• Syntax of Pop
• EXEC CICS Pop
• Handle
• END-EXEC.

119
EXEC Interface Block (EIB)

• CICS provides some system-related information to
  each task as EXEC Interface Block (EIB)
• Unique to the CICS command level
• EIBAID Attention- Id (1 Byte)
• EIBCALEN Length of DFHCOMMAREA (S9(4) comp)
• EIBDATE Date when this task started (S9(7)
  comp-3)
• EIBFN Function Code of the last command ( 2
  Bytes)
• EIBRCODE Response Code of the last command (6
  Bytes)
• EIBTASKN Task number of this task (S9(7) comp-3)
• EIBTIME Time when this task started (S9(7)
  comp-3)
• EIBTRMID Terminal-Id (1 to 4 chars)
• EIBTRNID Transaction-Id (1 to 4 chars)

120
Processing Program Table - PPT

• DFHPPT TYPEENTRY
• PROGRAM MAPSET name
• PGMLANG ASMCOBOLPLI
• RES NOFIXYES
• other options
• Eg.
• DFHPPT TYPEENTRY,PROGRAMTEST,
• PGMLANGCOBOL

121
PCT Entry

• DFHPCT TYPEENTRY
• TRANSID name
• PROGRAMname
• TASKREQpf6
• RESTARTyes/no ( TRANSEC 1 to
  64)
• RSLKEY 1 to 24 resource level key
• SCTYKEY 1 to 64 security key
• other options

122
PROGRAM CONTROL

123
Program Control Commands

• LINK
• XCTL
• RETURN
• LOAD
• RELEASE

124
LINK

• Used to pass control from one application program
  to another
• The calling program expects control to be
  returned to it
• Data can be passed to the called program using
  COMMAREA
• If the called program is not already in main
  storage it is loaded

125
LINK Syntax

• EXEC CICS LINK
• PROGRAM(name)
• COMMAREA(data-area)
• LENGTH(data-value)
• END-EXEC.
• Conditions PGMIDERR, NOTAUTH, LENGERR

126
XCTL

• To transfer control from one application program
  to another in the same logical level
• The program from which control is transferred is
  released
• Data can be passed to the called program using
  COMMAREA
• If the called program is not already in main
  storage it is loaded

127
XCTL Syntax

• EXEC CICS XCTL
• PROGRAM(name)
• COMMAREA(data-area)
• LENGTH(data-value)
• END-EXEC.
• Conditions PGMIDERR, NOTAUTH, LENGERR

128
RETURN

• To return control from one application program to
  another at a higher logical level or to CICS
• Data can be passed using COMMAREA when returning
  to CICS to the next task

129
RETURN Syntax

• EXEC CICS RETURN
• TRANSID(name)
• COMMAREA(data-area)
• LENGTH(data-value)
• END-EXEC.
• Conditions INVREQ, LENGERR

130
Level 0 Level 1 Level 2 Level 3
CICS
PROG A LINK RETURN
PROG C LINK RETURN
PROG B XCTL
Application Program Logic Levels
PROG D XCTL
PROG E RETURN
131
LOAD

• To load program/table/map from the CICS DFHRPL
  concatenation library into the main storage
• Using load reduces system overhead
• Syntax
• EXEC CICS Load
• Program(name)
• SET (pointer-ref)
• LENGTH (data-area)
• END-EXEC.
• Condition NOTAUTH, PGMIDER

132
RELEASE

• To RELEASE a loaded program/table/map
• Syntax
• EXEC CICS RELEASE
• PROGRAM(name)
• END-EXEC.
• Conditions PGMIDERR, NOTAUTH, INVREQ

133
COMMAREA

• Data passed to called program using COMMAREA in
  LINK and XCTL
• Calling program - Working Storage definition
• Called program - Linkage section definition under
  DFHCOMMAREA
• Called program can alter data and this will
  automatically available in calling program after
  the RETURN command
• ( need not use COMMAREA option in the return for
  this purpose )
• EIBCALEN is set when COMMAREA is passed

134
Communication With Databases

135
CICS - DB2

• CICS provides interface to DB2.
• DB2 requires CICS Attachment Facility to
  connect itself to CICS
• CICS programs can issue commands for SQL services
  in order to access the DB2 database.
• EXEC SQL function
• options
• END-EXEC

136
Operating system
CICS REGION
DB2 REGION
CICS Attachment Facility
App. Pgm. EXEC SQL..
DB2 Database
DB2 Database access by CICS
137
RCT Entry

• The CICS-to-DB2 connection is defined by creating
  and assembling the resource control table (RCT)
• The information in RCT is used to control the
  interactions between CICS DB2 resources
• DB2 attachment facility provides a macro
  (DSNCRCT) to generate the RCT.
• The RCT must be link-edited into a library that
  is accessible to MVS

138
DB2 - Precompiler

• Source Program (EXEC SQL...
• EXEC
  CICS...)
• DB2 Precompiler
• CICS command translator
• Compile By COBOL
• Linkedit by Linkage editor
• Load Module

139
QUEUES

140
Transient data Control

• Provides application programmer with a queuing
  facility
• Data can be stored/queued for subsequent internal
  or external processing
• Stored data can be routed to symbolic
  destinations
• TDQs require a DCT entry
• Identified by Destination id - 1 to 4 bytes

141
TDQs

• Intra-partitioned - association within the same
  CICS subsystem
• Typical uses are
• - ATI (Automatic Task Initiation) associated with
  trigger level
• - Message switching
• - Broadcasting etc
• Extra-partitioned - association external to the
  CICS subsystem, Can associate with any sequential
  device - Tape, DASD, Printer etc
• Typical uses are
• - Logging data, statistics, transaction error
  messages
• - Create files for subsequent processing by
  Non-CICS / Batch
• programs.

142
TDQs

• Operations
• Write data to a transient data queue (WRITEQ TD)
• Read data from a transient data queue (READQ TD)
• Delete an intra partition transient data queue
  (DELETEQ TD).

143
WRITEQ TD

• Syntax
• EXEC CICS WRITEQ TD
• QUEUE(name)
• FROM(data-area)
• LENGTH(data-value)
• SYSID(systemname)
• END-EXEC.
• Conditions DISABLED, INVREQ, IOERR, ISCINVREQ,
  LENGERR, NOSPACE, NOTAUTH, NOTOPEN, QIDERR,
  SYSIDERR

144
READQ TD

• Reads the queue destructively - Data record not
  available in the queue after the read.
• Syntax
• EXEC CICS READQ TD
• QUEUE(name)
• INTO(data-area) SET(ptr-ref)