Calculating virtual storage below the 16-MB line

This calculation produces an estimate of virtual storage constraints below the 16-MB line in the Db2 database services address space.

About this task

Most of the needed virtual storage is in extended private storage and storage above the 2 GB bar, including the buffer pool, the EDM pool, and almost all of the code and working storage. This is the difference between the total storage and the estimated region size. The estimated region size does not include extended private storage or storage above the 2 GB bar. It includes only the data set control block storage size and some of the code.

Procedure

To estimate the size of storage below the 16-MB line:

Use the following formula:

600 KB + (((MAX USERS + MAX REMOTE ACTIVE) * 298) / 1024) + (DSMAX * 0.016)

Example

The default, as calculated by the DSNTINST CLIST, is

600 KB + (((200 + 200) * 298) / 1024) + (20000 * 0.016 KB) = 1036 KB

If the scheduler work area (SWA) is above the 16-MB line, multiply the number of data sets by 0.016 KB; if the SWA is below the 16-MB line, multiply the number of data sets by 1.2 KB.

The CLIST calculations panel, DSNTIPC, displays storage sizes that are calculated by the DSNTINST CLIST.