Performance Tuning for Content Manager

228 Performance Tuning for Content Manager

8.6.21 Application heap size (APPLHEAPSZ)

Impact

DB - Medium

Description

This parameter defines the number of private memory pages that are available

for use by the database manager on behalf of a specific agent or subagent.

The heap is allocated when an agent or subagent is initialized for an application.

The amount that is allocated will be the minimum amount needed to process the

request given to the agent or subagent. As the agent or subagent requires more

heap space to process larger SQL statements, the database manager will

allocate more memory as needed, up to the maximum specified by this

parameter.

In a partitioned database environment, APP_CTL_HEAP_SZ is used to store

copies of the executing sections of SQL statements for agents and subagents.

SMP subagents use APPLHEAPSZ as do agents in all other environments.

Default values (range)

256 (16 - 60,000) 4-KB pages

To update

Run the following DB2 command:

db2 update db cfg for <database name> using APPLHEAPSZ <parameter

value>

Our recommendation

The Content Manager installation program sets this value to 4,096 for the Library

Server and the Resource Manager. Use this value initially.

Increase this if your applications receive an error indicating insufficient storage in

the application heap. APPLHEAPSZ is allocated out of agent private memory. Be

sure that you have enough private memory before increasing this number.