Please don't hijack discussions by adding unrelated questions to them. Fortunately I can split you into a new discussion.
Have you been through the documentation? Is there such a class as CachedThreadPool at all? I couldn't see anything about size in the relevant documentation at all.
which is a convenience class for executors, there is a couple of cached thread pools methods. If this is the method call being asked, then the executor service being returned has an asked default size of zero threads, and a max thread size of MAX INT threads.