A load module is an executable program stored in a partitioned data set program library. Creating a load module to execute only, will require that you use a batch loader or program management loader. Creating a load module that can be stored in a program library requires that you use the binder or linkage editor. In all cases, the load module is relocatable, which means that it can be located at any address in virtual storage within the confines of the residency mode (RMODE).

Once a program is loaded, control is passed to it, with a value in the base register. This gives the program its starting address, where it was loaded, so that all addresses can be resolved as the sum of the base plus the offset. Relocatable programs allow an identical copy of a program to be loaded in many different address spaces, each being loaded at a different starting address.