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High Performance Invocation of Modules From Within the Vm System Product Interpreter

IP.com Disclosure Number: IPCOM000099423D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-14
Document File: 2 page(s) / 70K

Publishing Venue

IBM

Related People

Modderkolk, AA: AUTHOR

Abstract

A method is disclosed which allows for a significant performance improvement in the invocation of nucleus-loaded Basic Assembler modules from either the VM System Product Interpreter (REXX) or programs compiled by the VM REXX Compiler for CMS (product number 5664-390).

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This is the abbreviated version, containing approximately 68% of the total text.

High Performance Invocation of Modules From Within the Vm System Product Interpreter

       A method is disclosed which allows for a significant
performance improvement in the invocation of nucleus-loaded Basic
Assembler modules from either the VM System Product Interpreter
(REXX) or programs compiled by the VM REXX Compiler for CMS (product
number 5664-390).

      When invoking another program by name from within a REXX
procedure, SVC202 services are used to find the program. The
advantage of nucleus-loaded modules is that their names are at the
top of the list, and thus found early in scanning the lists, and do
not need to be loaded from disk because they are pre-loaded in
virtual memory. However, even frequently used modules are invoked
scanning the lists each time and thus go through a sizeable path
length before the requested function is invoked.

      This method scans the lists only once and uses the System/370
LPSW machine instruction to invoke the nucleus-loaded program, using
the path length of that one instruction.

      The method of operation is shown as a flow diagram in Fig. 1
and as REXX statements in Fig 2.

      1. The module is NUCXLOADed through the NUCXLOAD command
hardware.

      2. NUCXLOAD does not return the entry point because CMS assumes
that SVC202 will be used to invoke it, i.e., the NUCXMAP (STACK
command is issued to list the date on all NUCXLOADed modules in the
stack. The stack is scanned for the specific module...