increase java heap memory command prompt

It is possible to increase heap size allocated by the JVM by using command line options Here we have 3 options

-Xms<size>        set initial Java heap size
-Xmx<size>        set maximum Java heap size
-Xss<size>        set java thread stack size

java -Xms16m -Xmx64m ClassName
In the above line we are setting minimum heap to 16mb and maximum heap 64mb