A z/OS memory dump contains the current state of the machine. The actual contents of the dump will depend on the address spaces and data spaces selected. The dump will also include any component traces running at the time the dump is taken. IBM generally recommends taking a synchronous dump instead of an asynchronous dump. A synchronous dump ensures that the memory contents do not change between the time the dump request is made and the time the dump is actually taken on the machine.

DUMP COMM=(description) 

R nn,JOBNAME=(OMVS,TCPproc,NFSSproc,NFSCproc,jobname*),CONT

R nn,DSPNAME=('OMVS'.*,'tcpproc'.*),CONT

R nn, SDATA=(PSA,SQA,LSQA,RGN,TRT,LPA,CSA,GRSQ,SUM,ALLNUC),CONT