MAXPROCUSER

MAXPROCUSER specifies the maximum number of processes that a single user (that is, with the same UID) can have concurrently active.

To improve performance, use MAXPROCUSER to limit user activity.

When selecting a value, consider these factors:

Set MAXPROCUSER to at least 16 to conform to the POSIX standard for CHILD_MAX, or to at least 25 to conform to the FIPS standard.
A low MAXPROCUSER value limits the number of concurrent processes that a user can run. A low value limits a user's consumption of processing time, virtual memory, and other system resources.
Some daemons or users run without UID(0), and might create many address spaces. In these cases, give the daemon ID a high enough PROCUSERMAX value in the OMVS segment.

A user with a UID of 0 is not limited by the MAXPROCUSER value because a superuser might need to be able to log on and use kernel services to solve a problem.

Though not suggested, the security administrator can give the same z/OS UNIX UID to more than one TSO/E user ID. Therefore, the number of users can be greater than the number of UIDs that are defined. Check with the security administrator; if users share UIDs, you will need to define a greater number of processes for each user.

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 PROCUSERMAX limit on a per-process basis. For example:

ALTUSER userid OMVS(PROCUSERMAX(nnnn))

For an example of MAXPROCUSER settings in BPXPRMxx, see Monitoring use of system resources.