The JES2 job queue

JES2 receives a job, places its JES2 control blocks on spool, and creates a job queue entry (JQE) on the JES2 job queue. JES2 uses a job queue index (JIX) based on the job number to more efficiently access the jobs on spool.

The queue entry for each job contains the job name, job priority, the IDs of the entry and execution nodes, a flag that indicates the held status of the job, pointers to JES2 control blocks on the spool, and the next JES2 process for which the job is eligible (transmission to another node in an NJE network, JCL conversion, execution, output processing, purging).

Batch jobs are selected for execution by initiators, each one running in a separate address space. Initiators are controlled by JES2 or by MVS™ workload management (WLM). Who controls the initiators is determined by the job class and by the MODE= parameter (JES or WLM) on the JOBCLASS statement. JES2 maintains two different queue organizations for all jobs awaiting execution to service the two different selection mechanisms:

All jobs are queued by job class, priority, and the order in which they finished conversion. This is the queue from which JES2 managed initiators select jobs for execution. See JES2 control of batch job initiation for more details.
Jobs awaiting execution in WLM managed job classes are also queued by their WLM assigned service class in the order they were made available for execution. This is the queue from which WLM managed initiators select jobs for execution. See WLM control of batch job initiation.

Started tasks and Time Sharing Users do not need initiators to begin execution. They are not affected by workload management nor other jobs in the queue but are initiated immediately by JES2.