ZUDFM OAF-display forward and backward chaining

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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.
  • The TPF system must have get file storage (GFS) pools enabled before you can use this command. Pools are not enabled until the system is cycled to CRAS state or above.

Format

Read syntax diagramSkip visual syntax diagram ZUDFM OAF/ fileaddrFCHfileaddr
Note: You can use either the ZUDFM OAF or the ZUDFM FCH command.
fileaddr
specifies an 8- or 16-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. For more information about the DBLCL macro, see TPFDF Installation and Customization.
    • The block trailer size of the file is less than 36 bytes. For more information about how to set the trailer size, see TPFDF Database Administration.
    • 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 FCH 4404E00D
System: UDFM0221I FCH F.A. 000000004404E00D ID FDF6 RCC 00 NBR FILEADDR FWDCHAIN BCKCHAIN HEADER PGM COMMAND LAST UPDATE --------------------------------------------------------- 000 000000004404E00D 00000000D8266581 00000000D82D28D1 4-BYTE FA BRCF ADD 29APR03 17.04.22 001 00000000D8266581 00000000D8093461 4-BYTE FA UFD7 CLOSE 29APR03 16.17.34 002 00000000D8093461 00000000D82D28C9 4-BYTE FA UFD7 CLOSE 29APR03 16.17.34 003 00000000D82D28C9 00000000D81D9501 4-BYTE FA UFD7 CLOSE 29APR03 16.17.34 004 00000000D81D9501 00000000D82D28D1 4-BYTE FA UFD7 CLOSE 29APR03 16.17.34 005 00000000D82D28D1 0000000000000000 4-BYTE FA UFD7 CLOSE 29APR03 16.17.34

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.
HEADER
Indicates whether the header has 4-byte or 8-byte file addresses.

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