System Erasure of Data

If DASD data erasure is in effect and you use any of the following items, the system overwrites the entire data set area:

  • The DELETE subparameter in the JCL DISP parameter of a data definition (DD) statement
  • The TSO DELETE command (for non-VSAM objects)
  • The SCRATCH macro
  • The SCRATCH control statement for the IEHPROGM utility program
  • The access method services DELETE command
For a sequential, partitioned, PDSE, or VSAM extended-format data set, if DASD data erasure is in effect, the system also overwrites the released area when you use any of the following:
  • RLSE subparameter in the JCL SPACE parameter in a DD statement to which a program writes
  • Partial release option in the management class
  • PARTREL macro

Prior to z/OS V2R1, EOS issued one channel program to erase one track. This process repeated until all tracks are erased. If the data set is large, this process could cause a large number of I/O requests. Starting in V2R1, the system can erase up to 255 tracks in a single channel program.