java heap space

hi, hi..I am using java studio enterprise 8 to work on a program.I want to increase the java heap size by using flag like "-Xms256m"But the IDE can't recognize such command...know why?thanks...
[236 byte] By [a35176a] at [2007-10-3 12:00:25]
# 1
found it.....:P
a35176a at 2007-7-15 14:36:49 > top of Java-index,Developer Tools,Java Compiler...