IMS Version 10 Memory Enhancements

(Originally posted 2007-06-13.)

Regular readers would know I’m working on my “Memory Matters in 2008” presentation, which is a re-spin of the ’07 Version. One of the things I talk about is IMS.

Thanks to my team mate Andy Wilkinson for this list of IMS Version 10 enhancements, all of which are virtual storage usage improvements.

Here are the more important items:

• OTMA message flood protection (prevents LSQA filling). This is retrofitted to IMS V9 by PTF.
• New IMS log records (x’4511′ and x’4512′) to report on control region memory use.
• IMS V10 acquires CSA for Fast Path resources in discrete pieces, rather than insisting it all be contiguous, which helps large Fast path customers

And here are some other, less important, IMS V10 items:

• ACBGEN supports 31-bit addressing for the first time, which helps programs which access thousands of databases.
• PCBs are passed from CICS to IMS using 31-bit addresses (instead of 24-bit addresses), which also helps programs which access thousands of databases.
• Some IMS modules move above the 16Mb line, saving about 100KB of virtual storage.
• Several IMS modules that used to reside in 24-bit common storage now reside in 31-bit common storage

The details of these are in the IMS V10 Release Planning Guide GC18-9717-00 available from here.