Your program uses the logical-record request control (LRC) block when the subschema usage mode is LR or MIXED. The LRC block provides an interface between the Logical Record Facility (LRF) and the application program. It passes information about a logical-record request to LRF and returns path status information about the processing of the request to the program. You use the LRC block in conjunction with the IDMS DB or IDMS DC communications block.
Your program instructs the DML precompiler to copy the data description (called SUBSCHEMA_LR_CTRL) of the LRC block from the data dictionary into program variable storage. You accomplish this by coding an INCLUDE IDMS (SUBSCHEMA_LR_CTRL) statement in your program.
Note: For more information on INCLUDE IDMS, see INCLUDE IDMS.
You should examine the LR_STATUS field of the LRC block after every call to LRF to determine the status of the call after processing. If the DBMS returns the value LR_ERROR, you should examine the ERROR_STATUS field of the IDMS DB or IDMS DC communications block.
The following figure shows the layout of the LRC block.
┌───────────┐ │ LRC BLOCK │ └───────────┘ Length Suggested Field Data Type (bytes) Initial Value ┌───────┐ │ 1 2 │ LRC-LRPXELNG Binary 2 (Halfword) 00 ├───────┤ │ 3 4 │ LRC-MAXVXP Binary 2 (Halfword) 00 ├───────┴──┐ │ 5 8 │ LRIDENT Alphanumeric 4 'LRC' ├──────────┴───┐ │ 9 16 │ LRVERB Alphanumeric 8 Spaces ├──────────────┴────┐ │ 17 32 │ LRNAME Alphanumeric 16 Spaces ├───────────────────┤ │ 33 48 │ LR-STATUS Alphanumeric 16 Spaces ├───────────────────┤ │ 49 64 │ FILLER ... 16 ... ├───┬───┬───────────┴─────┐ │ 65 ... (variable-length)│PXE Mixed ... ... └───┴───┴─────────────────┘ * word aligned
The LRC block contains the following fields:
Specifies the length of the LRC block
Specifies the length of the work area required to evaluate the WHERE clause.
Contains the constant LRC followed by a space.
Contains the verb passed to the Logical Record Facility.
Contains the name of the logical record being accessed.
Contains the path status of a logical-record request. Path statuses are 1- to 16-character strings; they can be either standard or defined in the subschema by the DBA. LRF provides three standard path statuses: LR_FOUND, LR_NOT_FOUND, and LR_ERROR.
Note: For more information on path statuses, see Logical-Record Clauses (WHERE and ON).
Work area used internally by the Logical Record Facility.
Contains the expansion of the WHERE clause; it can contain from 0 to 512 1-byte elements. The 512-byte limit can be raised or lowered by using the SIZE parameter of the INCLUDE IDMS (SUBSCHEMA_LR_CTRL) statement.
Note: For more information about the SIZE parameter and the INCLUDE IDMS statement, see INCLUDE IDMS.
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