Java memory allocation

The Java Virtual Machine takes two command line arguments which set the initial and maximum heap sizes: -Xms and -Xmx.
 You can add a system environment variable named _JAVA_OPTIONS (under Windows), and set the heap size values there.
For example if you want a 512Mb initial and 1024Mb maximum heap size you could use:
 
SET _JAVA_OPTIONS = -Xms512m -Xmx1024m