Programming Interface Information: This information is NOT intended to be used as Programming Interfaces of z/VM.

#### 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 HCPFMU/HCPFMP.
     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 HCPFMU/HCPFMP.
     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' LCDZEROS 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

This information is based on z/VM V6R1.0. Last updated on 18 Feb 2010 at 08:46:08 EDT.
Copyright IBM Corporation, 1990, 2008