ITM MVS TSO Part 1: Concepts and ISPF

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ITM - MVS TSO Part 1 Concepts and ISPF

• Module 1
• Chapter 1 Topic 1, 2, and 3
• Pages 1 45

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Objectives

• Differences Between
• Mainframe Computers
• Minicomputers
• Microcomputers
• Basic Workings of MVS Operating System
• Operate 3270 Terminal Emulator

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Topic 1 Intro to Mainframe Computer Systems

• Three classes of computer systems
• Mainframe
• Mini
• Micro
• What determines the size?
• Size of computer hardware configuration
• Nature of the applications
• Complexity of the system

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Hardware Configurations

• Two basic types of components
• Processors
• Input/Output (I/O) devices

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Processor Parts

• Central Processing Unit (CPU)
• Executes Instructions
• Main Storage
• Stores Instructions and Processed Data
• Device Controllers
• Allows CPU and Main Storage to connect to I/O
  devices

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Input/Output (I/O) devices

• Two Classes
• Provide Input and Output to System
• Terminals
• Printers
• Secondary Storage
• Tape Drives
• Disk Drives

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Typical Configurations

• Microcomputers
• Small, single user systems
• Simple processor
• Few input/output devices
• Minicomputers
• More than one terminal (multi-user)
• More main storage, etc.

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Typical Configurations

• Mainframe Computers
• More I/O devices
• Larger storage capacities
• System 360/370 family now 390
• Applications
• Broader storage
• Supports more users
• More diverse needs

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System Software

• Manages system software
• Operating System is the cornerstone
• Set of programs directly controlling computer
  operation
• MVS OS, including TSO
• Most complex OS in use
• Special programmers to maintain OS

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Mainframe OS Characteristics

• Virtual Storage
• Processor simulates main storage larger than
  actual real storage
• Multiprogramming
• More than one program executes at the same time
• Spooling
• Share access to I/O devices for programs that
  execute together

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Mainframe OS Characteristics

• Batch Processing
• Series of commands processed in a batch (job)
• JES (Job Sharing Subsystem) manages work flows
• Background processing
• Time-Sharing Option (TSO)
• User access by terminals
• Interactive processing or foreground processing

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Mainframe OSs

• DOS (Disk Operating System)
• Limited processing requirements
• Later versions known as DOS/VSE (virtual storage
  extended)
• OS (Operating System)
• MVS (Multiple Virtual Storage)
• Programmed jobs have own virtual storage address
  space
• Full range of processing possibilities
• VM (Virtual Machine)
• Virtual storage and multiprogramming simulate
  more than one computer system on a single real
  computer

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Topic 2 Intro to MVS and TSO

• MVS (Multiple Virtual Storage)
• OS that supports TSO
• Job
• Execution of one or more related programs in
  sequence
• Each program executed by a job is a job step
• Job Control Language (JCL)
• In a job, provides specifications necessary to
  process the job
• See Figure 1-6, Page 21

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Job Entry Subsystem (JES)

• Tracks jobs that enter the system
• Determines when they execute
• Sends output to proper location (printer, file,
  etc.)

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Job Entry Subsystem (JES)

• Two versions
• JES2
• JES2 single-processor systems without scheduling
  problems
• JES3
• for large multi-processor systems

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JES Job Scheduling Functions

• JCL statements and other input are held in the
  job queue
• JES determines when job is ready for processing
• JES presents the job for execution
• Printed output is collected in and output queue
• When job finishes, spooled output is printed

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JES Job Scheduling

• Can assign a job class and priority
• Higher classes execute first
• Job scheduling with JES3
• Specific times or execute after another job
  finishes
• Options for final disposition
• Specify SYSOUT Class
• Specifies the type of device for output

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Volume Table of Contents (VTOC)

• On all DASD (Direct Access Storage Device)
• Identifies each file on the volume
• VTOC entries provide
• File name
• Physical characteristics
• Block length
• Record length
• Organization
• Location on disk

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Data Sets and Data Set Names

• Another name for file
• Names consist of one or more qualifiers
• Maximum of eight characters long
• Separated by periods
• Maximum length, including periods is 44
  characters
• Allows for five eight-character qualifiers and
  four separating periods
• First qualifier is called the high-level qualifier

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Types of Files

• Two important to TSO
• Sequential
• Partitioned

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Sequential Files

• Records retrieved in the same order written
• To process a record in the middle, you must read
  all preceding records
• Examples
• Compiler listings
• Program output

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Partitioned Files

• Partitioned Data Set (PDS) or library
• Has a directory and one or more members
• Directory is a list of members in the library
• Each one to eight characters long
• To refer to a member
• Specify the data set name, followed by the member
  name
• i.e. TEST.COBOL (MKTG1200)

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Catalogs

• Stores names and info on commonly used files
• Cataloged data sets accessed by data set name
• If data set not cataloged
• Specify data set name and the volume serial
  (vol-ser) of the volume with the file

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Catalog Structure

• One Master Catalog
• Entries for
• System files
• User catalogs
• Any number of user catalogs
• Entries for
• Users data sets
• Catalog names can be an alias for more than one
  high-level qualifier

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Data Set Allocation

• Creating a new data set (allocation)
• Provides OS with info to locate and set aside
  space
• Allocating direct-access space
• In JCL, must indicate any data sets to allocate
• Use DD statements for each data set needed (see
  Page 25)

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Security

• Set passwords for sensitive files
• One Special security system
• RACF (Resource Access Control Facility)
• Multi-level password scheme
• Different levels of access for different users
• Automatic cycling of passwords
• Password expire after a specified period of time

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Storage Management Subsystem (SMS)

• Automates many tasks to manage DASD space
• All data sets must be cataloged
• Can assign three types of classes to data sets
• Data Class for basic data set characteristics
• Storage Class to specify performance required
• Management Class to specify when to backup or
  delete data sets

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TSO (Time-Sharing Option)

• Not an option anymore
• Allows users to share time and resources
• Unique address space for each user
• Terminal sessions
• Initiated with JCL unique to that user
• Includes DD statements to allocate data sets
  available to the user
• Specifies
• Terminal monitor program
• Commands or procedures to automatically execute

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TSO Commands

• Directly use by entering commands in the ready
  mode (ready prompt)
• Four basic categories
• Managing data sets
• Developing programs
• Processing background jobs
• Changing your TSO environment

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Command Procedures

• List of TSO commands that are executed together
• Can include procedure statements
• Provide features of high-level programming
  languages
• Symbolic variables
• Conditional logic
• Branching
• i.e. CLIST and REXX

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TSO Data Sets

• Standard data set naming conventions
• Adds other conventions
• Name format of user-id.name.type
• User-id is assigned to each TSO user
• Name to identify the data set
• Type to identify the type of data stored (see
  Figure 1-10, Page 30)
• TSO automatically adds user-id to data set names
• Unless name.type enclosed in parentheses

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TSO Session Manager

• 3270 terminals display one line at a time
• Starts at line 1
• Then down the screen until display full
• Recalls data cleared from the screen
• All line-orientated terminal activity recorded in
  a special journal
• Simple commands display journal entries

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ISPF

• Interactive System Productivity Facility
• Menu-driven, full-screen interface to TSO
• On-line tutorial

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Topic 3 Accessing TSO with 3270 Terminals

• 3270 Information Display System
• System of terminals, printers, and controllers
• Display stations and printers can be on one
  controller
• Controller connected to host computer system

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3270 Display Stations

• 3270 Terminals
• Display color
• Configure different options
• Selector light pens
• Extended highlighting

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3270 Printers and Controllers

• Use TSO to direct print output to printer
• Local print
• Prints contents of the screen on the printer
• Controller used is not important to users

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3270 Emulators

• Today, 3270 Emulators from a PC
• Acts as a 3270 Terminal
• Right CTRL key acts as the ENTER key
• Can be changed to actual ENTER key

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3270 Display Characteristics

• Displays 24 rows of 80 characters
• Treats screen as a series of fields
• Unprotected fields for data-entry in ISPF
• Identified as gt
• Protected fields for display only information
• Captions
• Data displayed by a program

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3270 Keys

• Five types of keys
• Data-entry keys
• Cursor-control keys
• Editing keys
• Attention keys
• Miscellaneous keys

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Data-Entry Keys

• Data-entry keys
• Letters
• Numbers
• Special characters

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Cursor-Control Keys

• Cursor-control keys
• Up, down, left, and right keys
• Tab and back-tab
• Backspace
• New-line
• Home (alt back-tab)

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Editing Keys

• Insert key (â)
• Delete key (a with editing mark)
• Erase-EOF key (end of field)
• Erase-Input

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Attention Keys

• Enter key
• Process data on the screen
• Program Function keys (PF)
• Press Alt key PF key for 1-12 (F keys on PC)
• Press PF key for 13-24 (not on PC)
• Most TSO functions use both keys for same
  function
• Program Access keys (PA)
• Do not send data to the system only an indicator
  of which key pressed
• PA1 is an interrupt key
• PA2 is to redisplay the screenignoring changes
• Clear key erases the screen and loses any data on
  the screen

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Miscellaneous keys

• Reset key

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Accessing TSO

• Physically connect (done already)
• Logically connect
• Enter T
• Enter user-id
• Enter password
• Enter to LOGON
• Notices may display
• LOGOFF to end (LOGON to reconnect)
• Automatic timeout

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Recap

• Differences Between
• Mainframe Computers
• Minicomputers
• Microcomputers
• Basic Workings of MVS Operating System
• Operate 3270 Terminal Emulator