JVM/Tomcat performance tuning

This is kind of a cross post between Tomcat and JVM tuning. I am currently running Tomcat 4.1.24 in production but I've noticed during the execution of the webapps that Tomcat/JVM uses a lot of memory. Not I "THINK" I've tuned it so that the JVM will use more memory if needed but I am not sure. Sometimes I can't tell if the JVM is doing a good job cleaning up after itself or not. Just in case, the application is written to set the variables to NULL anyway. Theoretically, JSP's should clean up after themselves (or the JVM) unlike an application, correct?

Run the JVM with the -verbosegc option, or even better the -Xloggc option, to log the garbage collection statistics. Tne analyze those statistics. The GC stat displayers like GcViewer and HPjtune help.
--Jack Shirazi
JavaPerformanceTuning.com