Type ASSEMBLE
Source Lines : 551
Fixes Applied : 1
Most Recent Version : Tuesday, December 12, 1978
Last Fix ID : [R09503DS]

Module

        DMSSTG

Function

       THE DMSSTG ROUTINE PROCESSES CMS CALLS TO DMSSTGST
       DMSSTGSB (STRINIT), DMSSTGAT, DMSSTGCL AND DMSSTGSV.

Attributes

       NUCLEUS RESIDENT, RE-ENTRANT

Operation

    IF  A CMS  ROUTINE  CALLS  THE STORAGE INITIALIZATION
    ROUTINE (STRINIT) IN DMSSTG, STRINIT
    RESETS THE  FREE STORAGE EXTENTS AND  EFFECTIVELY FREES
    ANY  STORAGE THAT  WAS  PREVIOUSLY  GETMAINED.

    IF A CMS ROUTINE CALLS DMSSTGCL IN DMSSTG, DMSSTGCL
    ISSUES STAE, SPIE, TTIMER, AND STAX CANCEL MACROES
    TO CANCEL ANY OUTSTANDING OS EXIT ROUTINES. IT ALSO
    CALLS DMSLGTA, DMSSLNAB, AND DMSFRET TO FREE ANY TXTLIB,
    MACLIB, OR LINK TABLES LEFT AROUND FROM PREVIOUS OS
    PROGRAMS. CONTROL IS THEN RETURNED TO THE USER.

    THE GETBLK  ROUTINE IN DMSSTG  SEARCHES THE  FREE CHAIN
    FOR A  BLOCK OF FREE STORAGE  LARGE ENOUGH TO  MEET THE
    CALLER'S NEEDS.   WHEN IT FINDS  ONE, IT  EITHER RESETS
    THE  BLOCK  LENGTH OR,  IF  ALL  THE BLOCK  IS  NEEDED,
    DELETES IT  AND RETURNS  CONTROL TO  THE CALLER.   IF A
    LARGE ENOUGH BLOCK  CANNOT BE FOUND
    CONTROL IS RETURNED TO THE CALLER WITH AN ERROR CODE IN
    REGISTER 15.

    THE  FREEBLK  ROUTINE  IN DMSSTG  RETURNS  A  BLOCK  OF
    STORAGE TO THE FREE CHAIN. IF  THE ADDRESS PASSED IT IS
    BAD, THE FREEBLK ROUTINE ISSUES AN ABEND.  IF THE BLOCK
    IT IS FREEING IS CONTIGUOUS TO  ANY OTHER FREE BLOCK IN
    CORE, THE FREEBLK ROUTINE WILL  COMBINE THE TWO BLOCKS.
    UPON SUCCESSFUL  COMPLETION CONTROL IS RETURNED  TO THE
    CALLER.

      PREVIOUS STORAGE ALLOCATION REQUESTS MAINTAIN A
       CHAIN OF POINTERS TO DISCONNECTED AREAS OF FREE CORE
       EACH LINK +00 IS FREPTR - POINTER TO NEXT LINK
                                  ZERO IF LAST IN CHAIN
                 +04 IS FRELEN - LENGTH OF FREE AREA
       FRELST POINTS TO THE FIRST LINK IN THE CHAIN
              OF DISCONNECTED AREAS
       FSTFRE HOLDS THE ORIGINAL BEGINNING OF USER FREE STORAGE
       LENFRE HOLDS THE LENGTH OF THAT AREA

       NUCON LOCATION MAINHIGH HOLDS THE LOWER BOUND FOR EXTEND.
       NUCON LOCATION FREELOWE (LOWEXT) HOLDS THE UPPER BOUND FOR
             GETMAIN.

Calls to Other Routines

       DMSSVT, DMSSAB, DMSFRE, DMSLGTA, DMSSLNAB