VU is the command to verify the Volumes Used in a VSAM file. you have to eneter in 3.4
VU PDS.PDS.XXXX.
It will give the result as
PDS.PDS.XXXX. XX.X% of XXX tracks in X extent
Allocated: X,XXX,XXX KB, Used: X,XXX,XXX KB (XXXX cylinders, X tracks)
Allocated: X,XXX,XXX KB, Used: X,XXX,XXX KB (XXXX cylinders, X tracks)