NAME       : HCPSTLBK
 DESCRIPTION: SEGMENT TABLE ENTRY LIST BLOCK
 DSECT      : STLBK
 FUNCTION   : THERE IS A SEGMENT TABLE ENTRY LIST BLOCK FOR
              EACH ACTIVE NAMED SAVED SYSTEM (NSS)
              OR DISCONTIGUOUS SAVED SEGMENT (DCSS).
              Within the block there are pointers to the STLTEs
              for each megabyte of address space in the NSS or
              DCSS.  STLTEs are packaged in sets of up to
              "STLTEper", each set in a separate block.
              STLSTEPT points to the 1st block of STLTEs.
              Subsequent pointers point to additional blocks
              of STLTEs.
              These STLTEs are mapped by HCPSTLTE COPY and
              the STLTE DSECT.
              The number of segments determines how much
              storage will be allocated to contain the STLTEs.
              THE SEGMENTS CAN BE SHARED OR EXCLUSIVE.
 LOCATED BY : SNTSTLPT  FIELD OF HCPSNTBK
 CREATED BY : HCPBSCBS - Build Segment Space STLBK
              HCPBSCSL  WHEN AT NSS OR DCSS IS FIRST REFERENCED
              AN STLBK IS ATTACHED TO THE USER VIA AN IMBED OPERATION.
              ENTRY POINT HCPBSIIM PERFORMS IMBED OPERATIONS.
 DELETED BY : HCPUIMSL  WHEN A NSS OR DCSS IS NO LONGER ACTIVE.
              AN STLBK IS DETACHED FROM THE USER VIA A REMOVE OPERATION.
              MODULE HCPUIMRM PERFORMS REMOVE OPERATIONS.
 RELOCATION CONSIDERATIONS : None

 STLBK DSECT
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Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      STLBK          SEGMENT TABLE ENTRY LIST BLOCK
0000    0 Signed       2 STLSTECT       Number of STLTEs for NSS/DCSS.
0002    2 Signed       2 *              Reserved for HCPBSC exclusively.
                                        HCPBSC builds STLBKs. As the
                                        builder, HCPBSC has exclusive
                                        access to the STLBK.
                                  During the building of
                                  STLBKs, HCPBSC may be
                                  manipulating more than 1
                                  STLBK at a time, and so may
                                  need more than 1 "index to
                                  current STLTE" field.  It is
                                  convenient to place the
                                  fields with their respective
                                  STLBKs.
                                  However, after the STLBK is
                                  built and made available,
                                  there may be more than 1 task
                                  touching the same STLBK.  In
                                  such cases, the "index" must
                                  not be in the STLBK because
                                  the tasks will be updating
                                  the "index" for their own
                                  needs, so each task must have
                                  its own "index" field.
0004    4 Address      4 STLSTEPT       Addresses of blocks filled with
                                        STLTEs. STLTEs point to page
                                        tables within PGMBKs. The STLTE
                                        is mapped by the HCPSTLTE COPY
                                        file.
                                  STLSTEPT points to the first
                                  STLTE.
      Areas for STLTEs are allocated dynamically, and the
      pointers to those areas are stored in STLSTEPT, and
      subsequent positions in storage.  The number of such
      areas, and the number of pointers to point to those
      areas, is determined by the maximum number of STLTEs
      (2048) and the maximum number of STLTEs per area
      (STLTEper).   STLnofPT will be calculated from these
      numbers, and sufficient pointers will be reserved.
          00000004       STLnofPT       (2048/STLTEper) nof pointers
                                        needed
0008    8 Address      4 * (3)          STLSTEPT already has one. This
                                        reserves the rest.
          00000003       STLSIZE        (*-STLBK+7)/8 STLBK SIZE IN
                                        DOUBLEWORDS

          
*** STLBK - SEGMENT TABLE ENTRY LIST BLOCK
*
*     +-------------+-------------+---------------------------+
*   0 |  STLSTECT   |/////////////|         STLSTEPT          |
*     +-------------+-------------+---------------------------+
*   8 |///////////////////////////////////////////////////////|
*     |///////////////////////////+---------------------------+
*     |///////////////////////////| 14
*     +---------------------------+
*
*** STLBK - SEGMENT TABLE ENTRY LIST BLOCK

 
Symbol         Dspl Value
-------------- ---- -----
STLnofPT       0004 00000004
STLSIZE        0008 00000003
STLSTECT       0000
STLSTEPT       0004