Gen support of z/OS 3.1 (mix of Gen 8.5 and 8.6 generated code)
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Gen support of z/OS 3.1 (mix of Gen 8.5 and 8.6 generated code)


Article ID: 278036


Updated On:


Gen - Host Encyclopedia Gen


When we migrated our Gen client/server applications to Gen 8.6 on the z/OS server side we left the generated code at 8.5 and just implemented the Gen 8.6 z/OS runtimes according to the migration/upgrade advice on this page: Gen™ 8.6 Encyclopedia > Host Encyclopedia > Host Encyclopedia Construction > DLLs, Compatibility, and Application Migration in HE (see section "Migrating from Gen 8.5").

We are migrating each load module to 8.6 generated code only when application changes are required to that module.

Everything has been running successfully under z/OS 2.5 and we now want to upgrade to z/OS 3.1. Will the Gen 8.5 generated code still run successfully?


The Gen 8.6 Technical Requirements Third-Party Software Version page refers to the Gen Compatibility Matrix and z/OS Compatibility Matrix  which state that Gen 8.6 supports z/OS 3.1 (V3R1) without any PTF requirements.
Gen 8.5 reached End Of Service on June 30, 2021 and so it was never tested with z/OS 3.1.

The Gen 8.5 generated code is working successfully under z/OS 2.5 and it is expected to continue to do so under z/OS 3.1.
However, because Gen 8.5 generated applications have never been certified with z/OS 3.1, if you do encounter problems you will need to regenerate the code using Gen 8.6.