IBM Mainframe Forum

How to choose VSAM organization type to use? When is KSDS,ESDS,RRDS,LDS most suitable? Like what's the best VSAM type to use for batch processing, cics, etc.

The organization type is better determined by access desired rather than whether it's batch or CICS. Sometimes you'll want sequential, other times random, other times a combination of both. There's an IBM redbook called VSAM Demystified that might be one of the best to look at.

KSDS is usually used when random access to data by a key is needed. ESDS is usually used for applications writing sequential data. RRDS is usually used when random access to data without a key is needed. LDS is rarely used by applications.

Asking

How to choose VSAM organization type to use?

is the exact opposite of the approach that should be taken. The first thing to determine is how does the data need to be organized? How will the data be written to VSAM? How will the data be retrieved from VSAM? Once you have the answers to these questions, that will suggest the organization that needs to be used.