CICS subpools

In each dynamic storage area, storage is arranged in subpools. The CICS® subpools are dynamically acquired as needed, a page at a time, from within the applicable dynamic storage area.

Most CICS subpools are in 31-bit (above-the-line) or 64-bit (above-the-bar) storage. The subpools in 24-bit (below-the-line) storage must be monitored more carefully because of the limited space available.

Individual subpools can be static or dynamic. Some subpools contain static CICS storage, which cannot be tuned. All the subpools are rounded up to a multiple of 4 KB in storage size. Include this rounding factor in any subpool sizing, or evaluation of storage size changes after tuning or other changes.

The CICS domain subpools statistics contain useful information about the size and use of the dynamic storage area subpools. The following topics list the subpools in each dynamic storage area and their use. You can use this information to identify the possible causes of excessive usage in individual subpools.