Mainframe, MVS and zOS Discussion

Hi,

I'm learning IMS and got to know that without using the SSAs we can insert, delete replace the segments in IMS? Can you please help to learn this concept.

You, usually, don't use ANY SSAs on a DLET call because a DLET will always delete the segment you just retrieved with a GET HOLD call. If you have retrieved more than one segment that' the time when you need an SSA to tell IMS that what segment you want to delete. This applies to a path call.

For an ISRT you'll use at least one unqualified SSA, naming the segment you are inserting. If there are no other SSAs, which parent(s) the new segment gets under depends on database position before the ISRT call. This way you can implicitly establish where a new segment goes by previous calls. However, it's recommended to tell IMS exactly where the new segments should go by including qualified SSAs for all the higher level segments when you do an ISRT.

For REPL you do not use SSAs. When the preceding GET HOLD only got one segment, program knows what segment is to be replaced, so no SSA is needed.

If the preceding GET HOLD was a path call, you might need SSAs for a REPL is , if it retrieves more than one segment.

Hope this helps.

Thanks Anuj - got it.

You're welcome!