WebSphere Message Brokers
File: ac55020_
Writer: Michael Gibson

Concept topic

This build: July 31, 2007 21:21:02

Stack storage

When a message flow thread starts, it requires storage to perform the instructions that are defined by the message flow nodes. This storage comes from the execution group's heap and stack size. The default stack size that is allocated to a message flow thread depends on the operating system that is used.

Windows platform On Windows, each message flow thread is allocated 1 MB of stack space.

Linux platform On Linux, each message flow thread is allocated 8 MB of stack space.

UNIX platform On UNIX, each message flow thread is allocated 1 MB of stack space.

z/OS platform On z/OS, each message flow thread is allocated 512 KB of downward stack space and 50 KB of upward stack space.

In a message flow, a node typically uses 2 KB of the stack space. A typical message flow can therefore include 250 nodes on z/OS, 500 nodes on UNIX systems and 500 nodes on Windows. This amount can be higher or lower depending on the type of nodes used and the processing that they perform.

In WebSphere Message Broker, any processing that involves nested or recursive processing can cause extensive usage of the stack. For example, in the following situations you might need to increase the stack size:
  • When a message flow is processing a message that contains a large number of repetitions or complex nesting
  • When a message flow is executing ESQL that calls the same procedure or function recursively, or when an operator (for example, the concatenation operator) is used repeatedly in an ESQL statement

You can increase the stack size to improve performance. For details, see:

Related tasks
Optimizing message flow response times
Related reference
Message flows
Notices | Trademarks | Downloads | Library | Support | Feedback

Copyright IBM Corporation 1999, 2007Copyright IBM Corporation 1999, 2007. All Rights Reserved.
This build: July 31, 2007 21:21:02

ac55020_ This topic's URL is: