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VSAM Demystified

Author: Craig Mullins | | February 2, 2015

VSAM is used “under the covers” of every DB2 for z/OS page set. VSAM is also used as the storage mechanism by some IMS databases. It is also used to store a lot of mainframe data outside the control of any DBMS. But there is a lot of confusion about what exactly VSAM is, how it can be used, and how it differs from a DBMS.

I wrote an article for IDUG Solutions Journal titled On VSAM and DB2 that offers some high-level details on the differences between the two. But if you are looking for a great, in-depth publication on VSAM there is a great redbook you should check out with the same name as this blog entry: VSAM Demystified.

This book is intended to be used as an initial point of reference for VSAM functions. It is sure a lot easier starting here than wading through the many IBM manuals on the subject. And it is less costly than some of the great books on VSAM out there. (For those interested in some good VSAM books for further research consider these: VSAM Access Method Services by James Martin, VSAM by Doug Lowe, and VSAM for the COBOL Programmer also by Doug Lowe).

Anyway, back to the IBM redbook: this book helps to demystify VSAM and gives you the information necessary to understand, evaluate, and use VSAM properly. It covers VSAM basics, performance issues, assists with VSAM problem determination, VSAM recovery, gives guidance on managing VSAM data sets, and even discusses issues like VSAM Record Level Sharing and DFSMStvs.

If you are looking for a concise, useful, and cost-effective resource to bolster your VSAM knowledge, you should download and read VSAM Demystified today!

This post was originally published on Craig Mullins blog at

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