Use this command to display the forward and backward chaining information
of a subfile or an 8-character (4-byte) hexadecimal file address.
Requirements and Restrictions
Output from the ZUDFM OAF command stops after 500 chains have been
displayed.
Format
- Note:
- You can use either the ZUDFM OAF or the ZUDFM FCH command.
- fileaddr
- specifies an 8-character hexadecimal file address.
Additional Information
- If you enter the ZUDFM OAF command without a parameter, chaining is
displayed beginning with the file address that is currently linked.
- The ZUDFM OAF command displays chaining information beginning with the
block in which the file address is linked or specified, and continues for all
other blocks along the forward chain.
- If you use the ZUDFM OAF command with a specified file address, that file
address becomes the currently linked file.
- Block trailer and command information will not be displayed under the
following conditions:
- The &ACPDBFS variable is set to 0 in the DBLCL macro. See TPFDF Installation and Customization for more information
about the DBLCL macro.
- The block trailer size of the file is less than 36 bytes. See TPFDF Database Administration for more information about
how to set the trailer size.
- Nodes are being displayed in a B+Tree index file.
Examples
This following example displays the forward chaining, backward chaining, or
both, of the currently linked file.
+--------------------------------------------------------------------------------+
|User: ZUDFM OAF |
| |
|System: UDFM0221I OAF F.A. F402D808 ID FDEC RCC 00 |
| |
| NBR FILEADDR PGM FWDCHAIN BCKCHAIN BLOCK TRAILER COMMAND |
| --------------------------------------------------------------- |
| 000 F402D808 QT19 000C05A9 000C05A5 25JUN97 11.40.42 CLOSE |
| 001 000C05A9 QT19 000C05A5 25JUN97 11.39.52 ADD |
| 002 000C05A5 QT19 00000000 25JUN97 11.40.42 CLOSE |
+--------------------------------------------------------------------------------+
The following describes the information provided in the previous
example:
- FA
- The file address of the block.
- ID
- The file ID of the block.
- RCC
- A 1-byte field that contains the record code check (RCC). This is a
1-byte value that is common to all the blocks that are being pointed to in the
subfile.
- NBR
- The relative number of the block in the chain.
- FILEADDR
- The file address of the block.
- PGM
- The program stamp of the block, which is held in the STDPGM field.
- FWDCHAIN
- The file address of the block to which this block is forward
chained.
- BCKCHAIN
- The file address of the block to which this block is backward
chained. (The BCKCHAIN field in the prime block points to the address
of the last block in the chain.)
- Note:
- The backward chain is not displayed if it is zero. This indicates that
the file does not use full backward chaining.
- BLOCK TRAILER
- The date and time in which the block was written to DASD.
- COMMAND
- Indicates the TPFDF macro for the function that was used to write the
block. In this example, CLOSE indicates the DBCLS macro or dfcls functions.
The following example displays the forward chaining, backward chaining, or
both, of a specific file address.
+--------------------------------------------------------------------------------+
|User: ZUDFM OAF/000C05A9 |
| |
|System: UDFM0221I OAF F.A. 000C05A9 ID FDEC RCC 00 |
| |
| NBR FILEADDR PGM FWDCHAIN BCKCHAIN BLOCK TRAILER COMMAND |
| --------------------------------------------------------------- |
| 000 000C05A9 QT19 000C05A5 25JUN97 11.39.52 ADD |
| 001 000C05A5 QT19 00000000 25JUN97 11.40.42 CLOSE |
+--------------------------------------------------------------------------------+
References
See the following for more information about linking to a subfile: