This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori 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: