Modifying Memory Allocation on Tomcat 5.x on Windows

A search for ‘tomcat 5 outofmemory windows‘ returns about 2000 hits, not one of them shows you how can increase the amount of memory allocated to Tomcat via the Apache Tomcat Properties applet when running on Windows (some point to this Tomcat configuration document which seems to be a bit out of date). Start –> Programs –> Apache Tomcat 5.0 –> Configure Tomcat –> Java. The “Initial memory pool” corresponds to the JVM -Xms option (~ initial Java heap size), the “Maximum memory pool” corresponds to the JVM -Xmx option (~ maximum Java heap size) and the “Thread stack size” corresponds to the JVM -Xss option. The picture book follows:


You can read more about the non-standard options on

8 thoughts on “Modifying Memory Allocation on Tomcat 5.x on Windows”

  1. Very interesting! FWIW, Tomcat 5.0.16 doesn’t have the “memory pool” text boxes, but of course I can still add the -Xms and -Xmx statements in the “Java Options” myself.

  2. You’re a life-saver. I normally only use Tomcat on *nix machines but I’ve had to take over a Windows server and trying to change this setting was driving me mad.

  3. How do you add a -Xmn840m to the options? I can add aditional -XX parameters but the -X do not seem to work. Thanks Richard

  4. What exactly is that means…What is the advantage in doing so?
    What background process takes place?

  5. Why I can’t set up maximun memory pool greater than 950MB? I’m working in Windows Server 2003. I think it is a limitation of Windows or any update of Windows.
    someone knows how to fix this in windows?

  6. Can somebody give me –> CLI command –> to Change “Maximum Memory Pool” –> For Example : From 512MB to 1024MB

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