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



Control Block Contents  

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
              HCPFTUSG when the full track cache address space
              is created.
              HCPBPBRN when an address space is expanded.
              HCPRPBSN when an address space is compressed.
 Deleted by : HCPASMDS when the address space is destroyed.


STD Control Block Content


Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      STD            Architected version of the
     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
          000STDES       STDPSM         X'00000100' Isolate private-space
          1... ....      STDSAEM        X'00000080' Isolate
                                        storage-alteration-event bit.
          .111 1111      STDSTLM        X'0000007F' Isolate segment-table
          .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
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
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
          .... ....      STD3STLM       X'FF000000' Isolate segment-table
          00FFFFC0       STD3STOM       X'00FFFFC0' Isolate segment-table
          .... ...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 V4R3.0. Last updated on 30 Apr 2002 at 18:32:34 EDT.
Copyright IBM Corporation, 1990, 2002