SEG37 | Back to Index page

| Prolog Control Block Contents SEG37 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.

SEG37 Prolog | Top of page

     NAME       : HCPSEG37
     DESCRIPTION: Segment Table Entry for 370
     DSECT      : SEG37
     FUNCTION   : The following maps the segment table entry in the
                  System/370 architecture.
                  The format of the 370 segment table entry is
                  architected and cannot be changed in any way
                  which violates the architecture.
     RELOCATION CONSIDERATIONS : None

SEG37 Control Block Content | Top of page

     SEG37 DSECT
    Top of page

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      SEG37          Segment Table Entry for 370
    0000    0 Signed       4 SEG3ENTR (0)   System/370 Segment Table Entry
    0000    0 Bitstring    1 *              Page table length in left nibble
                                            and right nibble must be 0.
    0001    1 Bitstring    1 *              Part of page table address
    0002    2 Bitstring    1 *              Part of page table address
    0003    3 Bitstring    1 SEG370ST       Segment table entry status for
                                            370 non-extended architecture.
                                            Leftmost 5 bits comprise part of
                                            the page table address. Rightmost
                                            3 bits are the status.
              .... .1..      SEG370PR       X'04' SEG370PR Segment is write
                                            protected
              .... ..1.      SEG370CO       X'02' SEG370CO Segment is a
                                            common segment
              .... ...1      SEG370IV       X'01' SEG370IV Segment is invalid
              00000004       SEG3LENT       *-SEG3ENTR Length of one 370 STE
    0004    4 Signed       4 SEG3NEXT (0)   Next 370 STE
              SEG3NEXT       SEG3PTOM       X'00FFFFF8' SEG3PTOM Isolate
                                            page-table origin in S/370
                                            architecture STE
              .... ...1      SEG3INVM       X'00000001' SEG3INVM Isolate
                                            segment-invalid bit in S/370
                                            architecture STE
              .... ..1.      SEG3COMM       X'00000002' SEG3COMM Isolate
                                            common-segment bit in S/370
                                            architecture STE
              .... .1..      SEG3PROM       X'00000004' SEG3PROM Isolate
                                            segment-protection bit in S/370
                                            architecture STE
              .... ....      SEG3PTLM       X'F0000000' SEG3PTLM Isolate
                                            page-table length in S/370
                                            architecture STE
              .... ...1      SEG3RSVM       X'0F000001' SEG3RSVM Reserved
                                            bits, must be 0 in any valid
                                            S/370 architecture STE END OF
                                            DEFINITION

SEG37 Storage Layout | Top of page

    *** SEG37 - Segment Table Entry for 370
    *
    *     +------+------+------+------+
    *   0 |//////|//////|//////|:370ST|
    *     +------+------+------+------+
    *
    *** SEG37 - Segment Table Entry for 370

SEG37 Cross Reference | Top of page

    Symbol         Dspl Value
    -------------- ---- -----
    SEG3COMM       0004 02
    SEG3ENTR       0000
    SEG3INVM       0004 01
    SEG3LENT       0003 00000004
    SEG3NEXT       0004
    SEG3PROM       0004 04
    SEG3PTLM       0004 00
    SEG3PTOM       0004 SEG3NEXT
    SEG3RSVM       0004 01
    SEG370CO       0003 02
    SEG370IV       0003 01
    SEG370PR       0003 04
    SEG370ST       0003

This information is based on z/VM 7.2.0 Last updated on 24 Jun 2020 at 09:30:25 EDT.
Copyright IBM Corporation, 1990, 2020