CDMAXP2X parameter

Summary

Default value

8

Parameter type

System

Where set

On User 0's parameter line

Related products

All

Introduced

Model 204 V6.1 or earlier

Description

The CDMAXP2X parameter indicates the maximum number-in powers of 2-of 6K pages allocated in virtual storage that will be used for the TBO constraints log, and in CCATEMP, if CDMAXP2X is greater than CDMINP2X. These pages are permanently allocated during initialization. Pages are compacted till their number exceeds CDMAXP2X.

When a constraints page becomes almost full it is split into two pages. When the number of pages exceeds 2**CDMAXP2X, the splitting process stops and records grow into overflow pages that never split, but may be merged when they become too empty. Overflow pages are not compacted, because they do not have basic records and thus do not participated in hashing. The only way to find data on overflow pages is to look through all cells.

For example:

• CDMAXP2X=0 sets the maximum number of pages to compact to one.
• CDMAXP2X=8 sets the maximum number of pages to compact to 256.

The minimum value is zero and maximum value is 16, which corresponds to 64K pages. The parameter is not resettable.

However, during initialization, if the value of CDMAXP2X is less than the value of CDMINP2X, then CDMAXP2X is automatically reset to the larger value of CDMINP2X. The following message is also issued:

M204.2777: CDMAXP2X PARAMETER RESET TO LARGER CDMINP2X

Increasing the number of compacted pages may save CCATEMP pages, however, compacting more pages may consume more CPU time. Rocket Software recommends setting the value of CDMAXP2X between 7 and 9 and testing your results.