what does "Process exited with status: 138" mean?

[David Jencks]

I've managed to come up with a way make the server just stop with  
"Process exited with status: 138".  Does anyone know what this means  
or how to find out what this means?

It might possibly be some kind of disk space problem or problem  
rotating log files but I don't really have an idea where to start  
looking.

mac osx, java 6.

thanks
david jencks