Programming Interface Information: This page documents intended Programming Interfaces that allow the customer to write programs to obtain the services of z/VM.

#### STD

Prolog

Control Block Contents
STD DSECT

Storage Layout

Cross Reference (Contains links to field and bit definitions)

#### STD Prolog

     Name       : HCPSTD
     Description: Architected version of the ESA/390
                  segment-table designation.
     DSECT      : STD
     Function   : This DSECT maps the ESA/390 segment-table
                  designation. The format of a segment-table
                  designation is architected, and described in the
                  Principles of Operation.
     Located by : CR1      is the STD for the primary address space.
                  CR7      is the STD for the secondary address space.
                  CR13     is the STD for the home address space.
                  ASTSTD   in an ASTE.
                  VMDPSTD  is the STD for a virtual CPU's current
                  primary address space.
                  PFXSXSTD is the STD for the system-execution space.
     Created by : HCPASMCR when an address space is created.
                  HCPSSMCR when the system-execution address space is
                  created.
                  HCPFMUSG when the full track cache address space
                  is created.
                  HCPHDTMA when an address space is expanded.
                  HCPHDTNL when an address space is compressed.
     Deleted by : HCPASMDS when the address space is destroyed.

#### STD Control Block Content

#### STD DSECT

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      STD            Architected version of the
                                            ESA/390
          ESA/390 mode STD - 4 bytes, 32 bits
    0000    0 Signed       4 STDES (0)      Entire STD
              .... ....      STDSWEM        X'80000000' Isolate
                                            space-switch-event bit
              000STDES       STDSTOM        X'7FFFF000' Isolate segment-table
                                            origin
              000STDES       STDPSM         X'00000100' Isolate private-space
                                            bit
              1... ....      STDSAEM        X'00000080' Isolate
                                            storage-alteration-event bit.
              .111 1111      STDSTLM        X'0000007F' Isolate segment-table
                                            length
              .1.. ....      STDSTUNT       64 Number of bytes in a "segment-
                                            table unit", the number of bytes
                                            in the smallest variation of the
                                            size of a segment table.
              .... ...1      STDSTL01       X'01' 2 64-byte blocks (to
                                            address 32M)
              ..11 1111      STDSTL3F       X'3F' 64 64-byte blocks (to
                                            address 1024M).
              .1.. ....      STDSTL40       X'40' 65 64-byte blocks (to
                                            address 1040M), also, the number
                                            of 64-byte blocks in one 4K page
                                            of segment table entries.
              .111 1111      STDSTL7F       X'7F' 128 64-byte blocks (to
                                            address 2048M).
              .... .11.      STDSTUNS       6 Number of bits to shift left in
                                            order to multiply by STDSTUNT.
                                            Also, number of bits to shift to
                                            convert between STE offset and
                                            corresponding STL value.
              ...1 1...      STDSXSTL       20+4 Bits to shift to convert
                                            between an isolated segment index
                                            and the corresponding segment-
                                            table length. Also used to
                                            convert between STL units and
                                            addressable bytes.
              ...1 .1.1      STDSXDWS       STDSXSTL-3 Bits to shift to
                                            convert between an isolated
                                            segment index (or number of
                                            addressable bytes) and
                                            doublewords of segment table
                                            space required.
              .... ..11      STDDWSTL       3 Bits to shift to convert
                                            between STL units and segment
                                            table length in doublewords.
              .... .11.      STDBYSTL       6 Bits to shift to convert
                                            between STL units and segment
                                            table length in bytes.
              ...1 ..1.      STDSXDSP       20-2 Bits to shift right an
                                            isolated segment index to obtain
                                            the displacement into the segment
                                            table of the applicable STE.
    0000    0 Bitstring    1 STD0           STD, byte 0
              1... ....      STDSWE         X'80' Space-switch event bit.
                                            When set, space-switch event
                                            program interruptions are
                                            recognized when space switches
                                            occur.
    0001    1 Bitstring    1 STD1           STD, byte 1
    0002    2 Bitstring    1 STD2           STD, byte 2
              .... ..1.      STDSSGRP       X'02' Subspace-Group bit. When
                                            set, indicates that the address
                                            space specified by the STD is
                                            part of a subspace group.
              .... ...1      STDPRIVS       X'01' Private-space bit. When
                                            set, prefixing, low-address
                                            protection, and fetch- protection
                                            override to not apply to DAT
                                            references.
    0003    3 Bitstring    1 STD3           STD, byte 3
              1... ....      STDSAE         X'80' Storage-alteration-event
                                            bit. When set, storage-alteration
                                            PER events in this address space
                                            are enabled via the
                                            storage-alteration-space control
                                            bit of CR9.
              00000004       STDSLEN        *-STDES Length in bytes of a STD.
              00000001       STDSSIZE       (STDSLEN+7)/8 Size in doublewords
                                            of a STD.
          The following maps the segment-table designation in the
          System/370 architecture.
              .... ....      STD3STLM       X'FF000000' Isolate segment-table
                                            length
              00FFFFC0       STD3STOM       X'00FFFFC0' Isolate segment-table
                                            origin
              .... ...1      STD3SWEM       X'00000001' Isolate
                                            space-switch-event bit

#### STD Storage Layout

    *** STD - Architected version of the ESA/390
    *
    *     +------+------+------+------+
    *   0 |STD0  |STD1  |STD2  |STD3  | 4
    *     +------+------+------+------+
    *
    *** STD - Architected version of the ESA/390

#### STD Cross Reference

    Symbol         Dspl Value
    -------------- ---- -----
    STDBYSTL       0000 06
    STDDWSTL       0000 03
    STDES          0000
    STDPRIVS       0002 01
    STDPSM         0000 000STDES
    STDSAE         0003 80
    STDSAEM        0000 80
    STDSLEN        0003 00000004
    STDSSGRP       0002 02
    STDSSIZE       0003 00000001
    STDSTLM        0000 7F
    STDSTL01       0000 01
    STDSTL3F       0000 3F
    STDSTL40       0000 40
    STDSTL7F       0000 7F
    STDSTOM        0000 000STDES
    STDSTUNS       0000 06
    STDSTUNT       0000 40
    STDSWE         0000 80
    STDSWEM        0000 00
    STDSXDSP       0000 12
    STDSXDWS       0000 15
    STDSXSTL       0000 18
    STD0           0000
    STD1           0001
    STD2           0002
    STD3           0003
    STD3STLM       0003 00
    STD3STOM       0003 00FFFFC0
    STD3SWEM       0003 01

This information is based on z/VM V5R2.0. Last updated on 12 Apr 2006 at 17:41:08 EDT.
Copyright IBM Corporation, 1990, 2005