This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
The run.bat (run.sh for linux) has a section for adding the JVM parameters including the heap size. Look for JAVA_OPTS in that file and add your JVM setting there. This is what i have on my local setup: