The default Java heap size given to Swat Analyze is -Xmx1024m (this is hardcoded, and is not to be confused with the heap size specified in the swat and swat.bat scripts).

For long traces and/or when you have lots of luns, 1024m may not always be enough. Could I increase the default? Technically, yes. However, for users that do not have much memory or swap space that could mean that they then can not even run the Swat Analyze at all. 1024m therefore is a decent starting value.

When your Analyze fails with ‘java.lang.OutOfMemoryError: Java heap space’, ignore the suggestion in  message ‘Rerun as
‘java -Xmx512m…’, since that though technically is correct, is not complete enough. Changing the swat/swat.bat scripts also will not solve this.

When using the GUI, select the ‘Settings’ tab, click on the ‘java_prm’ line, increase the -Xmx value (the highest I have been able to do is -Xmx2560m), click ‘Save’, and restart Analyze.

If you can’t use the GUI, go to file ‘options.sUSERID.ini’ and manually change the value after ‘java_prm’ and restart Analyze. 

Source/Kaynak : http://blogs.sun.com/henk/entry/swat_analyze_function_and_java