STD | Back to Index page

| Prolog Control Block Contents STD DSECT Storage Layout Cross Reference (Contains links to field and bit definitions) |
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 | Top of page

     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.
     RELOCATION CONSIDERATIONS : None

STD Control Block Content | Top of page

     STD DSECT
    Top of page

    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' STDSWEM Isolate
                                            space-switch-event bit
              000STDES       STDSTOM        X'7FFFF000' STDSTOM Isolate
                                            segment-table origin
              000STDES       STDPSM         X'00000100' STDPSM Isolate
                                            private-space bit
              1... ....      STDSAEM        X'00000080' STDSAEM Isolate
                                            storage-alteration-event bit.
              .111 1111      STDSTLM        X'0000007F' STDSTLM Isolate
                                            segment-table length
              .1.. ....      STDSTUNT       64 STDSTUNT 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' STDSTL01 2 64-byte blocks
                                            (to address 32M)
              ..11 1111      STDSTL3F       X'3F' STDSTL3F 64 64-byte blocks
                                            (to address 1024M).
              .1.. ....      STDSTL40       X'40' STDSTL40 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' STDSTL7F 128 64-byte blocks
                                            (to address 2048M).
              .... .11.      STDSTUNS       6 STDSTUNS 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 STDSXSTL 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 STDSXDWS 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 STDDWSTL Bits to shift to
                                            convert between STL units and
                                            segment table length in
                                            doublewords.
              .... .11.      STDBYSTL       6 STDBYSTL Bits to shift to
                                            convert between STL units and
                                            segment table length in bytes.
              ...1 ..1.      STDSXDSP       20-2 STDSXDSP 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' STDSWE 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' STDSSGRP Subspace-Group
                                            bit. When set, indicates that the
                                            address space specified by the
                                            STD is part of a subspace group.
              .... ...1      STDPRIVS       X'01' STDPRIVS 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' STDSAE
                                            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 | Top of page

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

STD Cross Reference | Top of page

    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 7.2.0 Last updated on 24 Jun 2020 at 09:31:57 EDT.
Copyright IBM Corporation, 1990, 2020