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Online Change of External Subsystems

IP.com Disclosure Number: IPCOM000044931D
Original Publication Date: 1983-Jan-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 15K

Publishing Venue

IBM

Related People

Denny, G: AUTHOR [+2]

Abstract

This article describes a method for operating a computing apparatus in which a plurality of subsystem instances are selectively connectable to an information management system to enable an application program running under the information management system to specify and change the subsystem to which service requests from the application are directed.

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Online Change of External Subsystems

This article describes a method for operating a computing apparatus in which a plurality of subsystem instances are selectively connectable to an information management system to enable an application program running under the information management system to specify and change the subsystem to which service requests from the application are directed.

The method comprises the steps of: (1) storing in DASD (direct access storage device) a procedure library (PROCLIB) member specifying in a language interface token (LIT code) the subsystem to which the application is to be connected; (2) copying the PROCLIB member into main storage for utilization by the information management system in establishing the connection between the application and a specified subsystem; (3) executing an operating system utility (IEBUPDTE) to change the PROCLIB member LIT code stored in DASD, and responsive to a first command (of the type/STOP), gracefully tearing down the connection to a sync point by quiescing applications connected to said specified subsystems; and thereafter (4) responsive to a second command (of the type/START), reading the PROCLIB member from DASD to update the PROCLIB member copy in main storage, and connecting the application to the newly specified subsystem.

Subsystem definition to and information management system, such as IBM IMS/VS is through the following member in the IMS/VS procedure library dataset (PROCLIB). The member is created by the installation (customer) using an OS utility (e.g., IEBUPDTE).

SUB1,SYS1,EXITS,TABLE,R,CRC. where SUB1 (Subsystem Name) is a one to four character MVS subsystem name that has been identified as a legitimate subsystem during the generation of the MVS operating system; SYS1 (Language Interface Token) specifies a four character alphanumeric installation defined language interface token; EXITS (External Subsystem Module Table) specifies the name of the subsystem attachment module table used by IMS/VS to load the specified modules, create the specified work areas and initialize the required control blocks; TABLE (Resource Translation Table) is an optional one to eight character alphanumeric name of a resource name exception table; R (Region Error Option) is an optional one-character error option specifying which action will occur if an application request is issued before the subsystem connection has completed. The valid parameters are: (R) the application will receive a return code indicating the request failed.

If the installation does not specify a Region Error, Option R is the elected IMS/VS default. (Q) IMS/VS will abend the application with a U3044 abend code and place the transaction on a queue to be processed when the subsystem connection is established. (A) The application program will be terminated with abend code U3047. Transaction input is discarded. CRC (Command Recognition Character) is an optional one-character external subsystem command recognit...