ZOS Xlp Codecache and ObjectHeap Changes

[AlenBadel]

Issue or pull request number: Related functional Pull Request: https://github.com/eclipse/openj9/pull/7585 Documentation changes Request: https://github.com/eclipse/openj9-docs/pull/412

Overview: Currently, on Z an additional [non]pageable argument is required when specifying a large page size for both the objectheap and codecache.

This isn't uniform with X, and P. There isn't really a reason for nonpageable to be an option within the codecache since it doesn't support nonpageable large pages.

It's also desirable that pageable large pages be used within the objectheap if both pageable, and nonpageable are available.

Release target: Eclipse OpenJ9 0.18.0

Applies to the following JDK versions: All

Applies to the following platforms: z/OS

[SueChaplain]

Hi @AlenBadel - please can you confirm whether any work is expected for this issue please. There is an open PR that I propose to close on the basis that it is very old and will need re-creating. If the work itself has been sidelined/refactored in some way, perhaps we can close this issue too and reopen at an appropriate time. Thanks