Programming Interface Information:
This information is NOT intended to be used as Programming Interfaces of z/VM. |
STLBK
Control Block Contents
STLBK DSECT
Cross Reference (Contains links to field and bit definitions)
STLBK Prolog
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 DELETED BY : HCPUIMSL WHEN A NSS OR DCSS IS NO LONGER ACTIVE.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 Control Block Content
STLBK DSECT
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 Storage Layout
*** STLBK - SEGMENT TABLE ENTRY LIST BLOCK * * +-------------+-------------+---------------------------+ * 0 | STLSTECT |/////////////| STLSTEPT | * +-------------+-------------+---------------------------+ * 8 |///////////////////////////////////////////////////////| * |///////////////////////////+---------------------------+ * |///////////////////////////| 14 * +---------------------------+ * *** STLBK - SEGMENT TABLE ENTRY LIST BLOCK
STLBK Cross Reference
Symbol Dspl Value -------------- ---- ----- STLnofPT 0004 00000004 STLSIZE 0008 00000003 STLSTECT 0000 STLSTEPT 0004
Copyright IBM Corporation, 1990, 2011