Activity levels of storage pools
The activity level of a storage pool refers to the number of active threads within that storage pool.
A single job with 500 threads takes up the same number of activity level slots as 500 jobs with a single thread. If the activity level is too low for the number of threads and jobs that are active, your threads are paged out of main storage and marked as ineligible for a short time. This can drastically affect the performance of your application.