SEG37

Prolog  

Control Block Contents  
   SEG37 DSECT

Storage Layout  

Cross Reference (Contains links to field and bit definitions)  

SEG37 Prolog

 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.

SEG37 Control Block Content

SEG37 DSECT

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' Segment is write protected
          .... ..1.      SEG370CO       X'02' Segment is a common segment
          .... ...1      SEG370IV       X'01' Segment is invalid
          00000004       SEG3LENT       *-SEG3ENTR Length of one 370 STE
0004    4 Signed       4 SEG3NEXT (0)   Next 370 STE
          00FFFFF8       SEG3PTOM       X'00FFFFF8' Isolate page-table
                                        origin in S/370 architecture STE
          .... ...1      SEG3INVM       X'00000001' Isolate
                                        segment-invalid bit in S/370
                                        architecture STE
          .... ..1.      SEG3COMM       X'00000002' Isolate
                                        common-segment bit in S/370
                                        architecture STE
          .... .1..      SEG3PROM       X'00000004' Isolate
                                        segment-protection bit in S/370
                                        architecture STE
          .... ....      SEG3PTLM       X'F0000000' Isolate page-table
                                        length in S/370 architecture STE
          .... ...1      SEG3RSVM       X'0F000001' Reserved bits, must
                                        be 0 in any valid S/370
                                        architecture STE
     END OF DEFINITION

SEG37 Storage Layout

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

SEG37 Cross Reference

Symbol         Dspl Value
-------------- ---- -----
SEG3COMM       0004 02
SEG3ENTR       0000
SEG3INVM       0004 01
SEG3LENT       0003 00000004
SEG3NEXT       0004
SEG3PROM       0004 04
SEG3PTLM       0004 00
SEG3PTOM       0004 00FFFFF8
SEG3RSVM       0004 01
SEG370CO       0003 02
SEG370IV       0003 01
SEG370PR       0003 04
SEG370ST       0003