Comparison of Executable and Relocatable Libraries

Created by programmers using HP Link Editor/XL commands.

Contain routines necessary for program execution.

Permit programs to share routines.

An RL stores routines in relocatable form, and an XL stores them in executable form.

An RL contains relocatable object code, which HP Link Editor/XL explicitly merges into an object module for each program that calls the routine. An XL contains sharable code, and each program refers to the same version of the code. When a program calls an XL routine, the loader reads it from disc into computer memory prior to execution.

When HP Link Editor/XL merges object modules from an RL into a program file, all the modules become part of one executable object module. An RL routine can share global data with a program. An XL routine can have its own global data area, but executable object modules cannot share global data with the program or other executable modules.

HP Link Editor/XL merges RL routines into a program file at link time. However, it only reserves space for pointers to XL routines in the External Reference Table at link time, and the loader resolves the references at run time.

HP Link Editor/XL can search a series of RLs during the linking phase. The loader can search a series of XLs during the execution phase if you provide it with an XL list.