The verbose suboption of -Xshareclasses gives the most concise and simple diagnostic output on cache usage.
>java -Xshareclasses:name=myCache,verbose -Xscmx10k HelloWorld [-Xshareclasses verbose output enabled] JVMSHRC158I Successfully created shared class cache "myCache" JVMSHRC166I Attached to cache "myCache", size=10200 bytes JVMSHRC096I WARNING: Shared Cache "myCache" is full. Use -Xscmx to set cache size. Hello JVMSHRC168I Total shared class bytes read=0. Total bytes stored=9284This output shows that a new cache called myCache was created, which was only 10 kilobytes in size and the cache filled up almost immediately. The message displayed on shut down shows how many bytes were read or stored in the cache.