/DATA_FORMAT=COMPRESS

    Use this qualifier for creating compressed save sets.
    You can specify the /DATA_FORMAT qualifier anywhere on the
    BACKUP command line.  The value "=COMPRESS" is required syntax.

    A compressed save set may be considerably smaller than
    the original data being saved, depending on the content
    of the data within the input files.  More CPU time is
    required to process a compressed save set.

    BACKUP uses the ZLIB compression algorithm.  The extent
    of processing done during compression can be modified
    using the /ZLIB_LEVEL qualifier.

    When restoring a save set, the /DATA_FORMAT qualifier is
    not required.  BACKUP will correctly choose to decompress
    a compressed save set or simply restore a non-compressed
    save set.