Open JMX console from this location: http://NAC-Hostname-or-IP:20203/
Default username and password for JMX is "nolio".
Go to com.sun.management:type=HotSpotDiagnostic
Under "java.lang.String" enter a desired file name and under "boolean" choose True. Click "Invoke" on the right.
The memory dump file will be saved on the NAC's home directory.
Go to noliocenter:type=info
Find "requestStackTrace" and click "Invoke" on the right.