http://www-01.ibm.com/support/docview.wss?uid=swg21519763
What is the -Xmn parameter?
Briefly, -Xmn decides the size of the young space in a JVM. When this parameter is not tuned, you may see some performance implications (for example, large spikes in the memory foot print).
For more information on -Xmn, refer to Tuning performance > Tuning the application serving environment > Tuning Java virtual machines
