TEMPBOP parameter

Number of CCATEMP pages reserved for backout data

Summary

Default value

1% of TEMPSIZE, rounded down to the nearest whole number of CCATEMP pages

Parameter type

System

Where set

On EXEC card or on User 0 parameter line

Related products

All

Introduced

Model 204 V7.4

Description

The TEMPBOP parameter defines the number of CCATEMP pages that must be free to start a sub-transaction.

An update transaction consists of one or more sub-transactions. A typical sub-transaction consists of reading a Model 204 page to be updated, writing the image of the page to the checkpoint stream, making an update to the page, creating back out and constraint entries in CCATEMP (in case the update is backed out) and writing the update to the journal stream.

If TEMPBOP pages are not free in CCATEMP when a sub-transaction starts, the following message is issued:

M204.0441: CCATEMP FULL

and the user's entire transaction is backed out.

The m204.0441 message indicates that you have a potential problem; for example, there is a runaway transaction, CCATEMP is too small, or a transaction is sitting in a wait holding large amounts of CCATEMP space. The update is cancelled but the Online is not forced down.

If TEMPBOP pages are not free in CCATEMP as the sub-transaction proceeds, the following message is issued:

M204.2904: INSUFFICIENT CCATEMP PAGES FOR BACKOUT DATA

and all in-flight transactions are backed out and the Online comes down. If this occurs, increase the sizes of CCATEMP and TEMPBOP.

TEMPBOP value

TEMPBOP can be set on the EXEC card PARMS or as a USER0 parameter. If not specified, TEMPBOP is calculated during Model 204 initialization, and the value is 1% of TEMPSIZE, rounded down to the nearest whole number of pages.

For example, if TEMPSIZE = 80, then TEMPBOP = 0, and if TEMPSIZE=141, TEMPBOP = 1.

MINIMUM value = 0
MAXIMUM value = 167772, based upon a maxmimum value of TEMPPAGE of 16777216