Browse Prior Art Database

Reentrant Variable Initialization

IP.com Disclosure Number: IPCOM000081166D
Original Publication Date: 1974-Apr-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Doggett, RH: AUTHOR

Abstract

This is a technique which uses existing facilities of OS/VS1 and OS/VS2 to initialize variables in a way that minimizes storage size, execution time and eases maintenance of reentrant programs.

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Reentrant Variable Initialization

This is a technique which uses existing facilities of OS/VS1 and OS/VS2 to initialize variables in a way that minimizes storage size, execution time and eases maintenance of reentrant programs.

Previously, such initialization was performed by allocating constants to be moved into an area of main storage which is dynamically acquired at execution time (e.g., via GETMAIN), requiring the execution of additional instructions to initialize variable fields which contain the addresses of other variable fields (such as OPEN and CLOSE parameter lists which must contain the addresses of data control blocks (DCBs)). These methods require increased storage size (for the constants and the additional instructions used to initialize the variables area), increased execution time (for the instructions executed to move data and to relocate address constants) and decreased maintainability (if a new address constant is to be added, instructions must be added to relocate it).

In the new method all variable data associated with the program is collected into a separate control section, which is link edited into a JOBLIB or into SYS1.LINKLIB with the load module attribute "not reusable". The reentrant program refers to these variables with a DSECT having the same structure as the variables section itself (the use of a macro to expand either the DSECT or the data itself simplifies this process and enhances maintainability). If the standard 18 full word r...