Vinoth, I'm assuming the memory error is occurring on the client side in your client java app. Your attachments didn't come through so I'm just making sure you aren't referring to a BIG-IP memory issue.
With that being said, the iControl library for Java utilizes the Apache Axis generated client bindings based on the iControl WSDL files. I do know that we have many customers using the iControl library for Java and I haven't heard of this issue before.
All the source is available in the iControl Assembly labs download section if you want to see what's going on in there.
Have you isolated this to a certain method call or calls that I could go by to try to replicate this?
-Joe
Nimbostratus