btw: using JBoss 3.2.1_tomcat
Look in the standardjboss.xml in the <JBOSS_DIST>//conf directory.
Change the MaximumSize(default is 100) under
<container-name>Standard Stateful SessionBean</container-name>
This will make it applicable to all Stateful session beans in ur server. To create for a single bean, create a configuration name that extends from Standard stateful session bean and change the max. size for that. Look in the docs for more info as to how to create a new configuration setting.