Guru asked me this question today about the Xms Xmx and Permspace parameters passed to java programs.
-Xms is the initial heap size and
-Xmx is the maximum
PermSpace is the area of the VM that is used to store data structures
and class information (not instances, but the class definitions
Keep in mind that the permanent area is not a subset of the heap.
The pictures on the page http://java.sun.com/docs/hotspot/gc/index.html
erroneously show permspace as a subset of the heap defined by -Xmx
parameter. This is a bug in the documentation (state February 2004).