Hello, I had a question about how z/OS handles physical memory for the same load module that is loaded at different virtual addresses in different virtual address spaces.
For example, let's say on the same z/OS system I have the following: CICS region A that has load module B loaded at virtual address x'3F400010'. CICS region B that has the same load module B loaded at virtual address x'3D400020'. More than likely there will be some differences in that same load module that has been loaded at different virtual addresses, since things like ADCONs and VCONs will resolve to different virtual addresses when the load module is brought into memory. However, there will probably be many virtual pages that are also identical between the two modules, if nothing in that virtual page needed to be adjusted by the loader. My question is, does z/OS have any functionality to detect the virtual pages that would be identical for these 2 load modules and then adjust the virtual page tables for CICS region A and B to point to the same physical frame and drop the duplicate frame? So for example, if the first 4k virtual page of load module B in CICS region A at x'3F400010' and the first 4k virtual page of load module B in CICS region B at x'3D400020' had the same data in it, would z/OS recognize this and cause the page tables for CICS region A at x'3F400010' and page tables for CICS region B at x'3D400020' to be adjusted to point to the same physical frame and then drop the other duplicate physical frame? I was under the impression that the answer was no, but one of the SYSPROGs here thought that z/OS had functionality to detect identical physical frames that hold instructions that different address spaces might be using and then do some physical memory savings like I am mentioning above. I tried doing some internet searches on this topic, and could not find any hits. If z/OS is doing this and someone has links to where this documented, I would appreciate a point in the right direction. Thanks, Tim Zielke CICS/MQ Systems Programmer Aon ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
