Label processing is handled by the I/O support routines of data
management (open, EOV, and close). Label processing consists of the
following basic functions:
- Converting input labels from ASCII to EBCDIC and converting output
labels from EBCDIC to ASCII
- Checking the labels on input tapes to
- Ensure that the correct volume is mounted
- Identify, describe, and protect the data set being processed
- Attempt to ensure maximum correctness and consistency of data
sets and their labels
- Identify compatibility conflicts with Version 3 or Version 4 standards
- Checking the existing labels on output tapes to
- Ensure that the correct volume is mounted
- Prevent overwriting of vital data
- Identify compatibility conflicts with Version 3 or Version 4 standards
- Creating and writing new labels on output tape
- For volumes in an automated tape library, comparing the external
volume serial number to the magnetically recorded internal label.
These processing functions are summarized in Table 1. The table shows the specific
labels that are processed for each function and which routines perform
the functions.
Although the default of each IBM-supplied installation exit is
to reject the volume, the exits can be modified to do additional label
processing. See ISO/ANSI installation exits for more information.
All volumes will be written with Version 3 or Version 4 labels.
For information about using tapes with other than Version 3 or Version
4 labels, see Compatibility with non-version 3 or non-version 4 volumes.
Table 1. ISO/ANSI
label processing by Open/Close/EOV routinesProcessing |
Volume Label |
Header Labels1 |
Trailer Labels1 |
---|
VOL1 |
VOL 2–9 |
User Volume Labels |
HDR1 |
HDR2 |
HDR3-9 |
UHL |
EOF1 or EOV1 |
EOF2 or EOV2 |
EOF3-9 or EOV3-9 |
UTL |
---|
First or only volume2 |
Checks labels on input tape |
Open |
Ignored3 |
Ignored3 |
Open |
Open |
Ignored3 |
Open |
EOV |
Bypassed |
Ignored3 |
EOV |
Checks existing labels on output
tape before overwriting |
Open |
Ignored4 |
Ignored4 |
Open |
Not read |
Not read |
Not read |
Not read |
Not read |
Open |
|
Writes new labels on output tape |
Open or user5 |
Not written |
Not written |
Open |
Open |
Not written |
Open |
Close or EOV |
Close or EOV |
Not written |
Close or EOV |
Compares the volume serial number
on the external volume label to the serial number in the tape volume
label7 |
Open |
N/A8 |
N/A8 |
N/A8 |
N/A8 |
N/A8 |
N/A8 |
N/A8 |
N/A8 |
N/A8 |
N/A8 |
Second or subsequent volumes6 |
Checks labels on input tape. |
EOV |
Ignored3 |
Ignored3 |
EOV |
Bypassed |
Ignored3 |
EOV |
EOV |
Bypassed |
Ignored3 |
EOV |
Checks existing labels on output
tape before overwriting. |
EOV |
Ignored4 |
Ignored4 |
EOV |
Not read |
Not read |
Not read |
Not read |
Not read |
Not read |
Not read |
Writes new labels on output tape. |
EOV or user5 |
Not written |
Not written |
EOV |
EOV |
Not written |
EOV |
Close or EOV |
Close or EOV |
Not written |
Not written |
Compares the volume serial number
on the external volume label to the serial number in the tape volume
label7 |
EOV |
N/A8 |
N/A8 |
N/A8 |
N/A8 |
N/A8 |
N/A8 |
N/A8 |
N/A8 |
N/A8 |
N/A8 |
Notes: - For read backward operations, the action on header and
trailer labels is reversed.
- Includes the first volume of concatenated data sets with
unlike characteristics when the user program has turned on the DCB
unlike attributes bit (DCBOFPPC). See z/OS DFSMS Using Data Sets .
- Label sequence is checked but contents are ignored.
- Operator must give Open/EOV permission to overwrite
VOL2–9 or ULV labels.
- User can create the label with the EDGINERS or IEHINITT
utility programs, or a user program.
- Includes the first volume of concatenated data sets when
the user has not turned on the DCB unlike attributes bit.
- Applies only to tape library.
- Not Available.
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