My experience with the 1.6.0 version of the JVM is that it does a very good job of automatically sizing the young generation, usually using 1/3 the heap size. So for 1.6.0 you don't need to set the young gen size. (The white papers I mentioned are fairly old and concern mostly 1.3.1 and 1.4.2, though the techniques described are still valid. Some of my later papers cover 1.5 and 1.6 and some of the tuning differences.)