You may want to enable MMapSessionManager to change its default parameters. You can also enable MMapSessionManager for a particular context if the server is running in single-process mode. To do so, edit the sun-web.xml file for the web application as in the following example. Note that persistence-type must be set to mmap.
<sun-web-app>
...
<session-config>
<session-manager persistence-type=”mmap”>
...
</session-manager>
...
</session-config>
...
</sun-web-app>
For more information about the sun-web.xml file, see Chapter 7, Deploying Web Applications