Setting JVM options for Servlet

[William Bondy]

I have a servlet application that requires tuning of JVM command line
operations to have decent performace. I need to tune things like the heap
size and garbage collection parameters. How do I do this, do I have to
change Tomcat startup files? Or is there a way to have contexts run in their
own jvm and use per context/jvm command line options?
 
 Thanks,
    Bill.