NikolaiBoats: It is obviously not hard to run a java program from a REXX script by just invoking the java command - either by using the SH environment, or by using bpxwunix. Either way, the java JVM will run and this calling environment has no impact on whether it will be zAAP/zIIP enabled: the -Xifa: switches can be used on the java command line to enable or force zAAP usage.

https://forum.sources.ru/index.php?showtopic=413860&view=findpost&p=3841326