Tomcat problem - java.lang.OutOfMemoryError: PermGen space

I think I get these errors when I do deployment and undeployment of wars in "hot deploy". Many articles point to this source in theserverside.com : "Explaining and Fixing java.lang.OutOfMemoryError: PermGen" ; there are some discussions in Resin which somehow blame leaks in CGLIB which is utilized by Hibernate. CGLIB claims a fix for this concerning ThreadLocals for release 2.1_03. I'm not yet familiar with ThreadLocals. I haven't tried newer CGLIB releases that has that fix. Maybe in another project utilizing Hibernate. I should also document in this blog how to manipulate the memory for the jvm using the command-line (one of those -Xm parameters..).