You can store frequently used modules of code or text in libraries.
Object libraries contain the object modules of frequently called routines.
Text libraries contain text modules that are frequently accessed. Sections of program source code that are used often can be stored in text libraries and then joined with your program during compilation. For more information on help libraries, see the VMS Librarian Utility Manual . Macro libraries contain macro definitions used as input to the assembler. The assembler searches specified macro libraries to resolve undefined macros in a macro source file.