Heap sizing | Read verbosegc output
Analyze verbose output
Verbose garbage collection is enabled by the -verbosegc (or alternatively, -verbose:gc) command line option.
To enable verbosegc using the WAS console, check the box...
Verbose garbage collection...on the JVM settings page...
Servers | Application servers | application_server | Server Infrastructure | Java and Process Management | Process Definition | Additional Properties | Java Virtual Machine.