MAXMMAPAREA

MAXMMAPAREA specifies the maximum number of data space pages that can be allocated for memory mapping of z/OS UNIX files. Storage is not allocated until memory mappings are active.

For MAXMMAPAREA, you can set a system-wide limit in BPXPRMxx and then set higher limits for individual processes. Use the RACF® ADDUSER or ALTUSER command to specify the MMAPAREAMAX limit on a per-process basis. For example:

ALTUSER userid OMVS(MMAPAREAMAX(nnnn))

The total amount of allocated mmap pages includes those pages in use by processes limited by the system limit MAXMMAPAREA and also those processes limited by the MMAPAREAMAX process limit for their OMVS segment.

When system limits are being monitored (LIMMSG=SYSTEM/ALL), the BPXI039I resource shortage message is only issued for processes limited by the MAXMMAPAREA value.

Because processes with process limits contribute to the total amount of allocated mmap pages, processes limited by the MAXMMAPAREA value might fail an mmap request before a BPXI039I message is issued. Also, processes with MMAPAREAMAX values for the OMVS segment might be successfully allocating mmap storage even though the BPXI039I message might be displayed with 100% usage.

The SHMEMMAX and MEMLIMIT parameters enable installations to manage the 64-bit space more effectively.