Linker (computing): Difference between revisions

Revision as of 12:46, 1 February 2025

Revision as of 23:48, 4 February 2025

Line 53:

== {{anchor|Consolidator}}Linkage editor ==

In IBM [[System/360]] through [[IBM Z]] [[Mainframe computer|mainframe]] environmentsoperating systems such as [[OS/360]], includingand [[z/successors|OS]]/360 forand theits [[z/Architecturesuccessors]] mainframes, this type of program is known as a ''linkage editor''. As the name implies a linkage ''editor'' has the additional capability of allowing the addition, replacement, and/or deletion of individual program sections. Operating systems such as OS/360 have format for executable load-modules containing supplementary data about the component sections of a program, so that an individual program section can be replaced, and other parts of the program updated so that relocatable addresses and other references can be corrected by the linkage editor, as part of the process.

One advantage of this is that it allows a program to be maintained without having to keep all of the intermediate object files, or without having to re-compile program sections that haven't changed. It also permits program updates to be distributed in the form of small files (originally [[card deck (computing)|card deck]]s), containing only the object module to be replaced. In such systems, object code is in the form and format of 80-byte punched-card images, so that updates can be introduced into a system using that medium. In later releases of OS/360 and in subsequent systems, load-modules contain additional data about versions of components modules, to create a traceable record of updates. It also allows one to add, change, or remove an [[overlay (programming)|overlay]] structure from an already linked load module.