Hello Michele,
Just incase you have not found the right place to put the environment variables, you can find the same in run.conf for "default" configuration of JBOSS server. I also hope you are aware that there is no one-size-fits-all -xmx and -xms setting. Moreover, just because we have a high RAM available, we must not set the heap size high. the simple reason is that the higher the heap size, more time will be taken by JVM to clear the objects in heap. There are many articles on the internet that would help you set a good heap size. You would need to simulate your production/ real life environment and keep adjusting your heap size untill you get a fix on one specification. the following list would be my consideration.
1. Number of concurrent users.
2. Size of objects getting created.
Based on this it would be better to profile the application and/ or do a load
test or stress test. This would ensure you have a better number for -xmx and -xms. Also do have a look at the Sun Specification that talks about rules regarding setting the heap size and of other parameters.
Between, I am still not sure if your previous message meant that the "system works like charm"
Would be happy to help. Kindly post a few more details.
Thanks and regards,
Raghav.V