Domain Knowledge and Overview of Mainframe (OS/390)


The main objective here is to give an overall idea about Mainframe concepts particularly in Basics of Mainframe so that there is a strong foundation for the Mainframe Domain. Some of the topics covered here are as below,

  • TSO/ISPF in OS/390
  • JCL in OS/390
  • SPUFI in OS/390
  • To understand the Basic fundamental concepts in Mainframe.
  • To understand TSO/ISPF in OS/390.
  • To understand creating, editing, viewing the datasets in OS/390 environment.


    What is a Mainframe?
    A Mainframe is.....
  • Basically a very large computer.
  • Process several million program instructions per second.
  • Used in Banking, Insurance, Airline and Railway Reservation systems in order to handle large programs with lots of data.


    What are the vairious Operating Systems?
  • MVS/SP (Multiple Virtual Storage/System Product),
  • MVS/XA (MVS/Extended Architecture),
  • MVS/ESA (MVS/Enterprise System Architecture),
  • S/360 (System 360),
  • S/370 (System 370),
  • OS/390
  • Z/OS


    What is OS/390?
  • It is an IBM Operating System most commonly installed on its S/390 line of mainframe server.
  • It was originally the MVS/ESA OS renamed and repackaged with an extensive set of utilities.
  • Uses TSO/ISPF for creating and editing, viewing the datasets.
  • Uses JCL for compiling and executing the COBOL load module.
  • Uses VSAM (Virtual Storage access method) for file handling in COBOL.
  • Uses DB2 for storing the information in the database.


    What is TSO/ISPF?
  • ISPF (Interactive System Productivity Facility )runs under TSO (Time Sharing Option) environment.
  • Allows you to perform most functions available in TSO.
  • Hierarchical menu driven system and is presented as formatted display consisting of protected and unprotected fields.
  • Perform many functions on datasets such as
    • Browsing,
    • Editing,
    • Printing, maintenance, scanning and comparing them against other datasets.
  • Provides friendly user interface to perform often complicated TSO commands.


    What is JCL?
  • JCL stands for Job Control Language.
  • It acts as the Interface between the COBOL program and the Operating System in Mainframe (mainly for Batch Processing).
  • Our Batch jobs are executed in Mainframe through JCL.
  • Mainly used for compiling and link editing COBOL Load modules.


    What is SPUFI?
  • SPUFI stands for SQL processing using File Input.
  • It is the DB2 (Data Base 2) interactive menu driven tool used by developers to create database objects.
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