java.lang.OutOfMemoryError: PermGen space after recompiling several times

Sometimes a java.lang.OutOfMemoryError: PermGen space exception occurs after recompiling the application a few times.

it seems that setting the following parameters to JVM starting tomcat fixes this issus:
-XX:+CMSClassUnloadingEnabled -XX:+CMSPermGenSweepingEnabled

see:
http://stackoverflow.com/questions/88235/dealing-with-java-lang-outofmemoryerror-permgen-space-error
