VSAM tutorials in Mainframe

VSAM Tutorial

Welcome to the VSAM Tutorial!!!

This tutorial will take your journey from absolute beginner to the advanced level so this Tutorial is a combination of – ‘VSAM tutorial for beginners’ as well as ‘VSAM tutorialĀ for Experienced’.

Most of the Training institutes charge you a minimum of $100 USD for VSAM Training but you can master complete VSAM tutorial for free.

Introduction of VSAM files

  • VSAM stands for Virtual Storage Access Method.
  • VSAM files are datasets which are NOT sequential Files.
  • Virtual Storage Access Method is an IBM DASD file Storage method.
  • The records in a VSAM file can be of Fixed Length or a variable Length.
Introduction of VSAM files

When You Should Choose a VSAM file over normal Sequential file?

  • When you want to do multiple operations in the file based on a particular key value, then you should choose a VSAM file.
  • If you want to update a particular record in the file or you want to delete your files as a normal activity, then you choose VSAM(Virtual Storage Access Method) file over sequential file because your intention is to perform multiple operations on the file.
  • VSAM files are much more powerful and advanced as compared to normal sequential files.
  • You can access the records of Sequential file in sequential order only but you can access the records of a VSAM file in multiple ways based on your requirement. You can access the records sequentially or using a key or dynamically in case of VSAM files.
  • There are multiple types of VSAM files and you can select the VSAM file based on your requirement.
  • When simple operations are involved like reading the file, writing the output to SPOOL(Simultaneous Peripheral Operations Online) or output device, then you can use sequential files but suppose you need a file wherein you need to frequently change the contents of the file periodically and multiple operations are required like different way of accessing etc. then you can use VSAM files.
  • If your file has a particular key value, then you can use that key value to access the records. You can access the records using primary key or even alternate keys.
  • If you need to update, insert or delete the records frequently, then VSAM is a better option compared to sequential files.
  • If you want to access the file directly using IPSF options 3.4, then VSAM is not a good choice.
  • You have to see the performance issues as well.

Important points about a VSAM file

  • You cannot directly modify the VSAM file using ISPF or using option 3.4 of TSO/ISPF.
  • VSAM files cannot access the data stored in Tape but can access the data from or to a DASD(Direct Access Storage Device).
  • The Records can be accessed in multiple ways like sequential order or you can also place the records in a logical sequence using a primary or secondary key or you can also access the records in random order or you can also access the records using RRN(Relative Record Number).

What will you learn in this Tutorial?

Complete VSAM Tutorial
Learn what is VSAM(Virtual Storage Access Method.
When you should use VSAM
We will start with the Introduction of VSAM files up to complete advanced levels.
Master the Data and Index Component of VSAM
You will learn about the Data and Index component of all the VSAM files.
Alternate Index
How to access the record using an alternate key?
How to delete an alternate index file?
Important functions of VSAM file
You will be able to change the properties of the VSAM file?
We will show you on How to print the records


  • Anyone who is a beginner on Mainframe with a basic knowledge of TSO/ISPF can learn easily from this tutorial.
  • The student or the learner should have basic knowledge of JCL(Job Control Language).
  • If you have basic knowledge of COBOL, it will be an added advantage while learning VSAM tutorial but it is not mandatory.