The ARCMVEXT installation exit receives control after DFSMShsm completes processing a level 0 volume during volume space management. It is called for system- and non-system-managed level 0 volumes, but is not called for level 1 or level 2 migration volumes.

Therefore, this exit can be called any time during a 24-hour processing day. If the processing defined by this exit must be confined to the automatic primary space management window, determine the time that you want to call the exit.

Remember that it is your responsibility to allocate and serialize the volumes passed to this exit.

You must write ARCMVEXT to be reentrant.