All jobs, with the exception of system jobs, run within subsystems. For work to start in an active subsystem, memory pools and at least one source of work entry point need to be established. Job queues are an example of a source of work.
The iSeries™ server ships with a default set of job queues, subsystems, and memory pools, which can allow work to begin as soon as the system is powered on.
You can tailor the subsystem and memory pool configurations to optimize your iSeries servers capabilities and performance. For example, if batch jobs are critical to the success of your business, you may want to allocate more memory for them to run. Or, you may determine that the number of jobs running at one time in your Qbatch subsystem should be lower so that those jobs can use the maximum amount of resources to run. Also, you can create job queues, subsystems, and memory pools specifically designed to complete specific types of work. For example, you can create a job queue called Nightreps, where nightly batch reports are sent to a subsystem called Nightrep that allocates memory exclusively for running these batch jobs.