Operator control of the batch job workload

The operator can ensure that the system resource manager has a sufficient number and variety of jobs to keep the system busy by varying the number of JES2 managed initiators and the classes from which they dequeue jobs. The mechanisms for such control are the JES2 commands to start, stop, set, and halt initiators ($S Ivvvv, $P Ivvvv, $T Ivvvv, and $Z Ivvvv). Each JES2 managed initiator controls the selection of one job at a time.

JES2 indirectly creates an address space for each active JES2 managed initiator. The operator can activate JES2 managed initiators and create additional batch job address spaces by means of the JES2 start initiator command ($S Ivvvv). In a similar manner, the operator can drain the JES2 managed initiators and cause termination of their address spaces by issuing the JES2 stop initiator command ($P Ivvvv).

The operator issues the halt initiator command ($Z Ivvvv) to deactivate a JES2 managed initiator, without terminating the address space (which is swapped out). This saves some time because JES2 need not recreate the address space if the operator starts the initiator later.

Table 1 summarizes the four useful commands for controlling batch workload (for syntax information, see z/OS JES2 Commands).

Table 1. JES2 Commands Useful in Controlling the Batch Job Workload
Desired Function	JES2 Command
Control the mix of batch jobs executable at the same time by assigning classes from which to select these jobs.	Set Initiator: $T INITvvvv
Activate JES2 managed initiators and cause creation of additional batch job address spaces.	Start Initiator: $S INITvvvv
Stop (“drain”) JES2 managed initiators and end batch job address spaces.	Stop Initiator: $P INITvvvv
Inactivate a JES2 managed initiator without terminating the address space	Halt Initiator: $Z INITvvvv

Note: The initiator identifier vvvv represents a 1- to 4-digit ID.

Use the DUPL_JOB= parameter on the JOBDEF statement or the $T JOBDEF,DUPL_JOB command to control whether JES2 is allowed to concurrently execute batch jobs of the same name in the same multi-access spool complex. Setting DUPL_JOB=DELAY instructs JES2 to wait for the first batch job to complete before starting the second with the same name.