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cwbriscoe10/05/20241 replyview on HN

You are correct, the OS is patched regularly but that doesn't require a recompile for the COBOL code, the OS ABI is stable and unchanging for legacy code. I have programs still running that hasn't been recompiled since 2005 (maybe earlier that is just what I noticed recently). When they upgrade hardware, they can do it per LPAR. They just shift the workloads over to other LPARS while they are upgrading another. Pretty much zero downtime.


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p_l10/06/2024

Yep. CICS, IMS, etc. all get updates along with z/OS itself, yet I had once plugged in an user exit written and compiled before 64bit z/OS existed and it just worked.