FZINXT - reset the read point on a direct access file

To reset the read point:

CALL FZINXT (LUN,MDSA1,MDSA2)

with    LUN:  logical unit number or Zebra stream ID

               the 2 word d/s address of the next d/s to be read,
      MDSA1:  word 1:  physical record number
      MDSA2:       2:  off-set within the record,
                         if this is zero the first d/s
                         starting in the record will be used