Rational Developer for System z
Enterprise COBOL for z/OS, Version 4.1, Programming Guide


Format of standard labels

Standard labels are 80-character records that are recorded in EBCDIC or ASCII. The first four characters are always used to identify the labels.

Table 1. Identifiers for standard tape labels
Identifier Description
VOL1 Volume label
HDR1 or HDR2 Data set header labels
EOV1 or EOV2 Data set trailer labels (end-of-volume)
EOF1 or EOF2 Data set trailer labels (end-of-data-set)
UHL1 to UHL8 User header labels
UTL1 to UTL8 User trailer labels

The format of the label for a direct-access volume is the almost the same as the format of the label group for a tape volume label group. The difference is that a data-set label of the initial DASTO volume label consists of the data set control block (DSCB). The DSCB appears in the volume table of contents (VTOC) and contains the equivalent of the tape data set header and trailer, in addition to control information such as space allocation.

Standard user labels

User labels are optional within the standard label groups. The format for user header labels (UHL1-8) and user trailer labels (UTL1-8) consists of a label 80 characters in length recorded in either:

  • EBCDIC on DASD or on IBM standard labeled tapes
  • ASCII or ISO/ANSI labeled tapes

The first 3 bytes consist of the characters that identify the label as either:

  • UHL for a user header label (at the beginning of a data set)
  • UTL for a user trailer label (at the end-of-volume or end-of-data set)

The next byte contains the relative position of this label within a set of labels of the same type; one to eight labels are permitted. The remaining 76 bytes consist of user-specified information.

Standard user labels are not supported for QSAM striped data sets.

related concepts  
Labels for QSAM files


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