IDSBK

Prolog  

Control Block Contents  
   IDSBK DSECT
   IDSEGENT DSECT
   IDSLTENT DSECT

Storage Layout  

Cross Reference (Contains links to field and bit definitions)  

IDSBK Prolog

 NAME       : HCPIDSBK
 DESCRIPTION: ISFC ID segment table
 DSECT      : IDSBK
 FUNCTION   : A simple segment-page table to locate address of a
              PTHBK or generate a unique ID for an ISFC resource.
 LOCATED BY : HCPBTB    contains an anchor for each table.
 CREATED BY : HCPBTB    as new entries are needed.
 DELETED BY : HCPBTB    as old entries are discarded.
 SERIALIZED : The ISFC global lock (HCPBDSGL).
 RELOCATION CONSIDERATIONS : None

IDSBK Control Block Content

IDSBK DSECT

Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      IDSBK          ISFC ID segment table
0000    0 Signed       4 IDSCOUNT       Total count of IDs in this table
0004    4 Signed       4 IDSHMARK       High water mark for this table
0008    8 Dbl-Word     8 *              Reserved The value of
                                        (IDSMAXSG*IDSEGBLN) for BLOCKMAP
                                        is 64*8 = 512
0010   16 Bitstring  512 IDSSTART       Reserve IDSEGENT space
          00000042       IDSSIZE        (*-IDSBK+7)/8 Size of IDSBK in
                                        doublewords
      FUNCTION   :
        This is the format for a single 'Segment Entry' in
        the IDSBK.
      LOCATED BY :
        IDSSTART  contains IDSEGENT entries.

IDSEGENT DSECT

Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      IDSEGENT       ISFC ID segment table
0000    0 Signed       4 IDSEGCNT       Count of IDs in this segment
0004    4 Address      4 IDSEGADD       Address of segment page
          00000008       IDSEGBLN       *-IDSEGENT Length of segment
                                        entry in bytes
      FUNCTION   :
        This is the format for a single 'Slot Entry' in
        the IDSBK.
      LOCATED BY :
        IDSSTART  contains IDSLTENT entries.

IDSLTENT DSECT

Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      IDSLTENT       ISFC ID segment table
0000    0 Address      4 IDSLTADD       Address of slot entry
                                        0=>available 1=>allocated,
                                        not a pointer
                                        >1=>allocated, pointer to
                                        entry
          00000004       IDSLTBLN       *-IDSLTENT Length of slot entry
                                        in bytes
      IUCV is limited to 64K paths, so each of these tables
      can only have 64K entries.  Each "slot" in a segment
      consists of a fullword, so each segment (4K page) can
      hold 1K slots.  Therefore, the maximum number of segment
      entries per table is 64 and the maximum number of slots
      per segment is 1024.
          00000040       IDSMAXSG       64 Maximum segment entries per
                                        table
          00000400       IDSMAXSL       1024 Maximum slots per segment
          00000001       IDSLTFUL       1 Zero implies slot available
                                        Non-zero implies slot allocated

IDSBK Storage Layout

          
*** IDSBK - ISFC ID segment table
*
*     +---------------------------+---------------------------+
*   0 |         IDSCOUNT          |         IDSHMARK          |
*     +---------------------------+---------------------------+
*   8 |///////////////////////////////////////////////////////|
*     +-------------------------------------------------------+
*  10 |                                                       |
*     =                       IDSSTART                        =
*     |                                                       |
*     +-------------------------------------------------------+
* 210
*
*** IDSBK - ISFC ID segment table
          
*** IDSEGENT - ISFC ID segment table
*
*     +---------------------------+---------------------------+
*   0 |         IDSEGCNT          |         IDSEGADD          |
*     +---------------------------+---------------------------+
*   8
*
*** IDSEGENT - ISFC ID segment table
          
*** IDSLTENT - ISFC ID segment table
*
*     +---------------------------+
*   0 |         IDSLTADD          | 4
*     +---------------------------+
*
*** IDSLTENT - ISFC ID segment table

IDSBK Cross Reference

Symbol         Dspl Value
-------------- ---- -----
IDSCOUNT       0000
IDSEGADD       0004
IDSEGBLN       0004 00000008
IDSEGCNT       0000
IDSHMARK       0004
IDSLTADD       0000
IDSLTBLN       0000 00000004
IDSLTFUL       0000 00000001
IDSMAXSG       0000 00000040
IDSMAXSL       0000 00000400
IDSSIZE        0010 00000042
IDSSTART       0010