The MAXUSER parameter in IEASYSxx defines the total number of jobs and started tasks that can run concurrently in the system. To enable APPC work to run concurrently with existing work in the system, increase the MAXUSER value by the number of APPC initiators that will be running in the system. You can calculate the number of APPC initiators based on the type of APPC transaction scheduler classes and the number of initiators defined to those classes.

For example, assume your installation has three APPC/MVS transaction scheduler classes, A, B, and C. During peak production, classes A and B are likely to schedule their maximum number of initiators, but class C is not active until third shift when not much else is running. If class A has a maximum number of 25 initiators and class B has a maximum of 50, you would add 75 to the MAXUSER parameter to enable the APPC work to run with existing work during peak production.