Hello Abishek,
just follow this guide:
http://wiki.sdn.sap.com/wiki/display/Java/NWDS+Troubleshooting
(see the topmost entry here).
You need to do this change in the instance profile that is located in /usr/sap/<SID>/SYS/profile folder, and the name of the file is always: <SID>_<central instance folder name>_<hostname>
I hope this helps.
Best Regards,
Ervin