Mainframe, MVS and zOS Discussion

Hello,

What are GSAM Files? Why do we need them? Can someone please help me with dome document available for GSAM files? Which can give basics about it.

Thanks,

As much as I know - GSAM files are used when you need check-point restart in your program...

GSAM stands for Generalized Sequential Access Method. I might sound a bit picky, however, there is nothing called as "GSAM Files" technically. They are "GSAM data-sets". GSAM data-sets can be considered as a "single occurence" of a IMS database. As DL/I was written as the main language for IMS DB, when an IMS program uses a GSAM data set, the program treats it like a "sequential nonhierarchic database". From that prespective, GSAM has no segments, no keys, and no parentage and that's obvious.

As Manoj said, GSAM can be used for check-point restart, however, your program must use symbolic CHKP and XRST calls if it uses GSAM. Basic CHKP calls cannot checkpoint GSAM databases.

Here is more on how to process GSAM in your program: Processing GSAM Databases.

Thankyou Anuj.