How to simulate low java heap space with java webstart?

Question

A client has java heap space problems. His environment seems to limit max heap space to 300 MB. My application should work with that, although it consumes more if it can. That's why I tried to limit the heap space by parameter to verify my claim. It is a webstart application, why I run from the console:

javaws -J-Xmx300m http://localhost:8080/application

However the according javaw process is using 400 MB of RAM. Is there something wrong with the parameter or can't that be used to really limit the heap space?

Answer 1

The parameter is working correctly, but as stated by @Jay the RAM usage is the sum of more as the heap space. See the linked question.