Permit cics mro session definition to have IOAREALEN > 32767, and/or, let session keep and reuse its HWM length TIOA

Issue: many additional cics freemains and getmains for mro session TIOAs are occurring, and burning cpu, after installing CICS TS 4.2.

Reason: new CICS TS 4.2 code is appending an extra 600 bytes, presumably to track hops between regions,
to many mro function ship datastreams sent to another cics region.
When this 600 bytes is added to the basic data already in a mro function shipped datastream with a length greater than 32177,
the datastream's cumulative length becomes greater than the mro session definition's maximum permitted IOAREALEN value of 32767.
The purpose of the IOAREALEN value is to keep a set length piece of TIOA storage available
to handle most function ship requests without incurring additional freemain/getmain overhead.
Since the cumulative TIOA length (after the 600 bytes is added) for mro sessions is now greater than 32767 for long length Temp storage items or vsam file records,
it is now impossible to avoid the extra freemains/getmains for TIOA storage for such mro sessions.

Suggested Resolutions: Either, or both, of the following enhancements would eliminate the need to do extra freemains/getmains for mro session TIOAs:
a) increase the permitted value for IOAREALEN on mro session definitions from the current 32767 to a larger value.
a value of 36840 (36K - 24 bytes) would be sufficient for QORs, queue-owning-regions, and FORs, file-owning-regions.

b) add logic to permit a mro session to keep the high water mark longest TIOA getmained for the mro session.
This would, in effect, tell cics to self tune the IOAREALEN value in favor of reduced cpu usage, rather than reduced storage usage.
CICS would have to be notified of this self tuning desire by adding a new parm to the mro session definition, or, by coding a mro session IOAREALEN=99999.