XSUBK | Back to Index page

| Prolog Control Block Contents XSUBK 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.

XSUBK Prolog | Top of page

     NAME       : HCPXSUBK
     DESCRIPTION: Expanded Storage Usability Map
     DSECT      : XSUBK
     FUNCTION   : This map is used to keep track of the allocation
                  of Expanded Storage. Each map corresponds to one
                  increment of XSTORE and can therefore represent
                  up to 64Meg of expanded storage.
     LOCATED BY : XDRUMAPT located in the HCPXDRBK.
     CREATED BY : HCPESCDI during initialization processing.
     DELETED BY : HCPESCDI if no expanded storage is configured
                  to the system.
     RELOCATION CONSIDERATIONS : None

XSUBK Control Block Content | Top of page

     XSUBK DSECT
    Top of page

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      XSUBK          Expanded Storage Usability Map
                 The following are bit maps that represents the
                 allocation of one increment of Expanded Storage
                 (up to 64 megabytes).
                 Each bit position represents the allocation state
                 of a block of XSTORE.
    0000    0 Bitstring    1 XSUALMAP (2048)
                                            XSTORE availability map. When a
                                            bit's value is "1" then the
                                            corresponding block is allocated.
    0800 2048 Bitstring    1 XSUERMAP (2048)
                                            XSTORE error map. When a bit's
                                            value is "1" then the
                                            corresponding block is in error.

XSUBK Storage Layout | Top of page

    *** XSUBK - Expanded Storage Usability Map
    *
    *     +-------------------------------------------------------+
    *   0 |                                                       |
    *     =                       XSUALMAP                        =
    *     |                                                       |
    *     +-------------------------------------------------------+
    * 800 |                                                       |
    *     =                       XSUERMAP                        =
    *     |                                                       |
    *     +-------------------------------------------------------+
    *1000
    *
    *** XSUBK - Expanded Storage Usability Map

XSUBK Cross Reference | Top of page

    Symbol         Dspl Value
    -------------- ---- -----
    XSUALMAP       0000
    XSUERMAP       0800

This information is based on z/VM 7.2.0 Last updated on 24 Jun 2020 at 09:31:52 EDT.
Copyright IBM Corporation, 1990, 2020