Type ASSEMBLE
Source Lines : 149
Fixes Applied : 0
Most Recent Version : Thursday, December 7, 1978
Last Fix ID : [Unmodified]

Module

       DMTSTO

Function

        THE DMTSTO  MODULE IS  THE SERVICE  ROUTINE WHICH
        RESERVES PAGES  OF FREE  MAIN STORAGE  FOR USE  BY
        CALLING TASK PROGRAMS. TASK PROGRAMS FREE PAGES OF
        MAIN  STORAGE  BY  SIMPLY  CLEARING  TO  ZERO  THE
        ASSOCIATED MAP BYTE IN THE MAIN STORAGE MAP.

Attributes

       REUSABLE, NON-INTERRUPTABLE

Operation

       ON A REQUEST FOR MAIN STORAGE RESERVATION,  DMTSTO
       IMMEDIATELY SUSPENDS THE  CALLING TASK'S EXECUTION
       THROUGH THE  FREEZE SVC FUNCTION. WITH  THE ACTIVE
       PSW MASKS SET OFF,  DMTSTO INSPECTS  THE REQUESTED
       PAGE ENTRIES IN THE MAIN STORAGE MAP. IF THE PAGES
       ARE  FREE,  THEY  ARE RESERVED  FOR  THE  TASK  BY
       INSERTING THE CALLING TASK'S ID IN EACH MAP ENTRY.
       IF SOME PAGE REQUESTED IS NOT  FREE AT THE TIME OF
       THE REQUEST PROCESSING, NO  PAGES ARE RESERVED AND
       AN  ERROR CONDITION  IS  RETURNED  TO THE  CALLING
       TASK.  (IT IS  THE RESPONSIBILITY  OF THE  CALLING
       TASK TO RETRY THE REQUEST IN THIS CASE.)    DMTSTO
       EXITS TO THE DISPATCHER.

Calls to Other Routines

       NONE