FREEVOL specification - Key = '8029'

FREEVOL specifies whether to allow other jobs to read freed volumes of a multivolume tape file as the volume is dismounted by the job.

When you code FREEVOL, # must be one, LEN must be one, and PARM contains one of the following values:
X'01'
Requests that volumes be dequeued at the end of the job step
X'02'
Requests that when reading a multivolume data set, the system finish reading the current volume and then dequeue the volume serial number and demount the volume. This makes the volume immediately available to another job in another system. An attempt by the same task to reprocess the volume using the same JCL DD statement will result in an abnormal end.
Example: To specify that the data set volume is to be freed as it is dismounted, code:
KEY    #     LEN   PARM
8029   0001  0001  02