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Higher than expected I/O in CICS region containing a Liberty profile enabled JVM server

Technote (troubleshooting)


You experience excessive I/O (EXCP) in your CICS region when you enable a JVMSERVER resource that is configured for the WebSphere Application Server Liberty profile.


High I/O in CICS region with a Liberty profile enabled JVM server


By default, WebSphere Application Server Liberty profile monitor periodically checks for configuration and application changes by reading the z/OS UNIX® file system.


JVM server

Diagnosing the problem

You see the EXCP count rising for the CICS region even though the region is performing no work.

You have a JVMSERVER resource enabled that is configured with the WebSphere Application Server Liberty profile, the JVM profile contains an entry for WLP_INSTALL_DIR.

Resolving the problem

Monitoring is controlled by elements in the Liberty profile server.xml file. Application monitoring is controlled by the <applicationMonitor> element and configuration update is controlled by the <config> element. You have a number of options to reduce I/O.

Edit the server.xml file, that is found by default in WORK_DIR/CICS_APPLID/JVMSERVER_NAME/wlp/usr/servers/defaultServer. If you have set WLP_USER_DIR in the JVM profile, append servers/server_name to value to find server.xml (where server_name is either "defaultServer" or the value of in the JVM profile).

Add or change the elements as follows:

  • If you are not using the dropins directory to deploy your web applications, disable monitoring of the dropins directory:

    <applicationMonitor dropins="dropins" dropinsEnabled="false">

  • Increase the configuration monitoring interval and the application monitor polling rate:

    <config monitorInterval="5s" updateTrigger="polled"/>
    <applicationMonitor dropins="dropins" dropinsEnabled="false" pollingRate="5s" updateTrigger="polled"/>

  • If your Liberty server configuration is static and you will not be performing any updates while the server is active, disable dynamic configuration monitoring:

    <config updateTrigger="disabled"/>

Note: If you want to use CICS bundles to install your web applications, application monitoring update trigger (applicationMonitor updateTrigger) and configuration monitoring update trigger (config updateTrigger) must be set to polled.

Further information can be found in the Controlling dynamic updates section of the WebSphere Application Server V8.5 information center.

Product Alias/Synonym

CICS/TS CICS TS CICS Transaction Server

Document information

More support for: CICS Transaction Server

Software version: 5.1

Operating system(s): z/OS

Reference #: 1620233

Modified date: 18 December 2012

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