Java Heap Memory Increase

Hello,

While running a long simulation, I got this following error,

>> exception in thread "AWT-EventQueue-0" java.lang.OutOfMemory: Java heap space"

On searching for help I followed the steps on

http://www.mathworks.se/support/solutions/en/data/1-18I2C/

But unfortunately, I still see that my Max. Memomry as 128 mb and not 256 mb as written in the java.opts file. Should this file contain only one line as

-Xms256m

and nothing else?

Thanks in advance!

P.S: Version I am using is Matalb 7.5 (R2007b)