How to increase the heap size of a Java Vuser
Use -Xms for setting minimum and -Xmx for setting maximum heap size
To modify the heap sizes for the Virtual Users themselves in a Java-based script (e.g., RMI, EJB, Corba), go to the Run-Time Settings and add the following in the Additional VM Parameters edit box:
-Xms256M -Xmx256M
How tio increase teh JVM memory to have maximium heap size?