Your box is WAY enough to run what you have.
Even with the default JVM settings for stack, it's surprising that you are running out of memory. What happens in your JSP? Are you processing a large set of data? How much mem does the JVM take sitting idle?
BTW - It may not be the true solution, but you can adjust the JVM startup parms for mem on the command line. Set
JAVA_OPTS=-Xmx192m or something like that before calling run.sh/run.bat.