Playing with JVM heam size

Java programs executes in JVM uses Heap of memory to manage the data. If your Java program requires a large amount of memory, it is possible that the virtual machine will begin to throw OutOfMemoryError instances when attempting to instantiate an object. The default heap size if 1 MB and can increase as much as 16 MB.

Java heap space setting from command line:

1. -Xms for initial heap size
2. -Xmx for maximum heap size 
3. -Xss<size>   for set java stack size
    

Initial heap size 128m, max heap size 256m:

java -Xms128m -Xmx256m MyApp

Initial heap size 256m, max heap size 256m:

java -Xms128m -Xmx256m MyApp

Max heap size can't be less than initial heap size:

java -ms256m -mx128m MyAppError occurred during initialization of VM
Incompatible initial and maximum heap sizes specified