DX1BK | Back to Index page

| Prolog Control Block Contents DX1BK DSECT Storage Layout Cross Reference (Contains links to field and bit definitions) |
Programming Interface Information: This information is NOT intended to be used as Programming Interfaces of z/VM.

DX1BK Prolog | Top of page

     NAME       : HCPDX1BK
     DESCRIPTION: Minidisk extent index level 1.
     DSECT      : DX1BK
     FUNCTION   : A DX1BK entry points to a DX2BK which can contain
                  up to 128 minidisk extents.
     LOCATED BY : MPEDX1BK  - HCPMPEBK pointer to DX1BK.
     CREATED BY : HCPMSMIP  When a Diagnose 244 is issued by the user.
     DELETED BY : HCPAMD44  During an identify pool function the
                  previous DX1BK will be deleted if any.
                  HCPMSMDP  During storage reset operation.
     RELOCATION CONSIDERATIONS : None
     COMMENTS   :

DX1BK Control Block Content | Top of page

     DX1BK DSECT
    Top of page

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      DX1BK          Minidisk extent index level 1.
    0000    0 Signed       4 DX1HPRBN       Highest PRBN contained in the
                                            second level page.
              00000004       DX1LENET       *-DX1HPRBN Length of this entry.
    0004    4 Signed       4 DX1NXTET (511) Next entry in this block.
    0800 2048 Bitstring    4 DX1DX2XT (0)   Description of the second level
                                            structure (DX2BK location packed
                                            with the extent count).
    0800 2048 Address      3 DX1DX2BK       Address of the second level page
                                            which contains up to 128 minidisk
                                            extents. Bits 0-23 are used as an
                                            address.
    0803 2051 Bitstring    1 DX1PGECT       Count of entries in a DX2BK block
                                            starting with 1. Zero indicates
                                            an empty DX2BK block.
              00000004       DX1LENE2       *-DX1DX2BK Length of this entry.
              1111 1111      DX1CTMSK       X'000000FF' Mask to isolate
                                            count.
              00FFFF00       DX1DX2AM       X'FFFFFF00' Mask to isolate DX2BK
                                            address.
    0804 2052 Signed       4 DX1DX2NT (511) Next entry in this block.
              00000200       DX1NUMET       4096/(DX1LENET+DX1LENE2) Number
                                            of entries in the DX1BK.

DX1BK Storage Layout | Top of page

    *** DX1BK - Minidisk extent index level 1.
    *
    *     +---------------------------+---------------------------+
    *   0 |         DX1HPRBN          |                           |
    *     +---------------------------+                           |
    *   8 |                                                       |
    *     =                       DX1NXTET                        =
    *     |                                                       |
    *     +--------------------+------+---------------------------+
    * 800 |     DX1DX2BK       |:PGECT|                           |
    *     +--------------------+------+                           |
    * 808 |                                                       |
    *     =                       DX1DX2NT                        =
    *     |                                                       |
    *     +-------------------------------------------------------+
    *1000
    *
    *** DX1BK - Minidisk extent index level 1.

DX1BK Cross Reference | Top of page

    Symbol         Dspl Value
    -------------- ---- -----
    DX1CTMSK       0803 FF
    DX1DX2AM       0803 00FFFF00
    DX1DX2BK       0800
    DX1DX2NT       0804
    DX1DX2XT       0800
    DX1HPRBN       0000
    DX1LENET       0000 00000004
    DX1LENE2       0803 00000004
    DX1NUMET       0804 00000200
    DX1NXTET       0004
    DX1PGECT       0803

This information is based on z/VM 7.2.0 Last updated on 24 Jun 2020 at 09:28:01 EDT.
Copyright IBM Corporation, 1990, 2020