A subsystem processes jobs from a job queue based on sequence number. A subsystem can have more than one job queue entry and can therefore allocate more than one job queue.
The maximum number of jobs from a queue is specified by the Maximum active jobs MAXACT parameter on the Add Job Queue Entry (ADDJOBQE) or the Change Job Queue Entry (CHGJOBQE) commands. You can also control how many jobs of each priority can be active by using the Maximum active priority MAXACTx parameters. For example, if MAXACT=10, MAXACT5=2, and there are three jobs on the job queue at priority level 5, then only two of them can become active at any given time.
The subsystem processes jobs from the job queue with the lowest sequence number first. When all of the jobs that are on the job queue have been processed, or when the maximum number of jobs from the queue is reached, the subsystem processes jobs from the queue with the next higher sequence number.
The sequence continues until the subsystem has processed all of the available job queue entries or until the subsystem has reached its limit of jobs that can be running or waiting in the subsystem. The number of jobs that can be running or waiting is determined by the Maximum active jobs (MAXACT) parameter in the subsystem description. In some cases the sequence is interrupted as jobs end or are transferred. Creating, holding, and releasing job queues can also change the sequence of job queues processed.