Due to the length of time ANZJVM can run, it is highly possible that a JVM ends before ANZJVM is able to finish. In the event that the JVM ends, ANZJVM returns the JVAB606 message (that is, JVM ended while processing ANZJVM) along with the data that it was able to obtain.
There is also no upper limit on the number of classes a JVM can handle. If there are more classes than can be handled, ANZJVM should return the data that can be handled along with a message letting you know there was additional information not reported. When the data requires truncating, ANZJVM returns as much information as possible.
The internal parameter is restricted to 3600 seconds (one hour) in length. The number of classes that ANZJVM can return information about is limited by the amount of storage on your system.