MAXPROCSYS

MAXPROCSYS specifies the maximum number of processes that can be active at the same time.

You can manage system resources by limiting the number of processes that the system is to support. The values that you specify for MAXPROCSYS, MAXPROCUSER, and MAXUIDS are interrelated. When selecting a value for MAXPROCSYS, remember that these processes are needed:

The initialization process (BPXOINIT).
/usr/sbin/init, for starting and processing.
exec sh to run a shell script.
The process in which the shell script runs.

Plan on one process for each daemon (for example, inetd and cron) that you start from a shell script such as /etc/rc. In addition, each shell user needs a minimum of three processes and possibly a few more for piping between shell commands.

Do not specify a higher value for MAXPROCSYS than your system can support because most processes use an entire MVS address space. This value will vary, depending on your environment. If you set the value too high, failures (EAGAIN) for fork or spawn might occur because WLM could not provide enough fork initiators.

Start of change Note that the maximum number of namespaces that are allowed on a system is derived from the MAXPROCSYS value. That limit is half of the MAXPROCSYS value at the time that z/OS UNIX was started. The namespace limit is not affected by dynamic changes to the MAXPROCSYS limit, although a shutdown and subsequent restart of z/OS UNIX will update the namespace limit based on the MAXPROCSYS limit at that time. End of change

Dynamically changing certain BPXPRMxx parameter values explains how to dynamically change the MAXPROCSYS value.

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