LCDA

Prolog  

Control Block Contents  
   LCDA DSECT

Storage Layout  

Cross Reference (Contains links to field and bit definitions)  

LCDA Prolog

 Name       : HCPLCDA
 Description: Locate data area
 DSECT      : LCDA
 Function   : Maps the contents of the Locate data
              area.
 Located by :
              HCCWADDR - The Locate CCW data address field
              contains the address of the locate
              data area.
 Created by :
              Storage for this control block cannot be
              specifically allocated/deallocated using
              HCPGETST/HCPRELST.
              Paging I/O manager -
              The data area resides in the HCPPIOBK which
              is allocated by HCPRDA.
              Track cache manager -
              Data area is part of a larger free storage
              area used to build FBA channel programs
              which is allocated in modules HCPFTU/HCPFTP.
 Deleted by :
              Storage for this control block cannot be
              specifically allocated/deallocated using
              HCPGETST/HCPRELST.
              Paging I/O manager -
              The data area resides in the HCPPIOBK which
              is allocated by HCPRDD.
              Track cache manager -
              Data area is part of a larger free storage
              area used to build FBA channel programs
              which is deallocated in modules HCPFTU/HCPFTP.
 Serialized :
              Paging I/O manager -
              EXPLCKFG - The paging I/O manager uses the exposure
              block lock to serialize this data area.
              Track cache manager -
              TCMTSLK  - Track cache lock
 Comments   :
              Paging I/O manager -
              The Locate data area resides in the HCPPIOBK.
              Each Locate CCW address field contains the
              address of the Locate data
              area within that PIOBK.
              Track cache manager -
              None

LCDA Control Block Content

LCDA DSECT

Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      LCDA           Locate data area
0000    0 Bitstring    8 LCDAREA (0)    Locate data area
     Byte 0 (Operation byte)
     Although defined as BITs, the contents of the operation byte are,
     architecturally, multiple codes.
0000    0 Bitstring    1 LCDOP          Operation byte
          .... ....      LCDZEROS       X'00' Operation byte, bits 0 - 3
          .... 1111      LCDOOC         X'0F' Operation byte, bits 4
                                        through 7 ------- Codes for use
                                        with LCDOOC
          .... ...1      LCDOCWD        X'01' Write data
          .... ..1.      LCDOCRR        X'02' Read Replicated Data
          .... .1..      LCDOCFD        X'04' Format defective block
          .... .1.1      LCDOCWC        X'05' Write and Check Data
          .... .11.      LCDOCRD        X'06' Read data -------
     Byte 1 (Locate Replication Count)
0001    1 Bitstring    1 LCDRPCNT       Replication count
     Bytes 2 and 3 (Block Count): Block count is the number of addressable
     blocks to be processed.
0002    2 Bitstring    2 LCDBKCNT       Block count
     Bytes 4 through 7 (Block address): Block address is the addressable
     block number of the first block to be processed in the data space.
0004    4 Bitstring    4 LCDBLOK        Block address
     Length equates
          00000008       LCDBSIZE       *-LCDAREA Size of LCDA in bytes
          00000001       LCDSIZE        ((*-LCDAREA)+7)/8 Size of LCDA in
                                        DWs

LCDA Storage Layout

          
*** LCDA - Locate data area
*
*     +------+------+-------------+---------------------------+
*   0 |LCDOP |:RPCNT|  LCDBKCNT   |         LCDBLOK           |
*     +------+------+-------------+---------------------------+
*   8
*
*** LCDA - Locate data area

LCDA Cross Reference

Symbol         Dspl Value
-------------- ---- -----
LCDAREA        0000
LCDBKCNT       0002
LCDBLOK        0004
LCDBSIZE       0004 00000008
LCDOCFD        0000 04
LCDOCRD        0000 06
LCDOCRR        0000 02
LCDOCWC        0000 05
LCDOCWD        0000 01
LCDOOC         0000 0F
LCDOP          0000
LCDRPCNT       0001
LCDSIZE        0004 00000001
LCDZEROS       0000 00