Loader (computing) - Definition and Overview

In computing, a loader is a program that performs the functions of a linker program and then immediately schedules the resulting executable program for action (in the form of a memory image), without necessarily saving the program as an executable file.

Loader programs are useful for prototyping, testing, and one-off applications. One such program was an integral part of Gene Amdahl's original OS/360 operating system, and this loader facility was continued through OS/360's descendants including MVT, MVS and z/OS.