Allocate executable storage properly

[ifakhrutdinov]

Proposed changes

Some storage that is intended to be executed is not allocated with the EXECUTABLE=YES option, can lead to ABENDs when certain z/OS options are set.

This PR changes the code which allocates such storage to allocate it with EXECUTABLE=YES.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

PR Checklist

Please delete options that are not relevant.

• If the changes in this PR are meant for the next release / mainline, this PR targets the "staging" branch.
• My code follows the style guidelines of this project (see: Contributing guideline)
• I have commented my code, particularly in hard-to-understand areas
• Relevant update to CHANGELOG.md
• My changes generate no new warnings

Testing

You will need a z/OS system where the special diagnostics for non-executable storage has been enabled.

Do the following:

• Regression testing of ZIS;
• Cancel a ZIS instance to trigger the address space resource manager; no ABENDs should occur.