Dynamic and static linking

You can use XL Fortran to take advantage of the operating system facilities for both dynamic and static linking.

Dynamic linking means that the code for some external routines is located and loaded when the program is first run. When you compile a program that uses shared libraries, the shared libraries are dynamically linked to your program by default. Dynamically linked programs take up less disk space and less virtual memory if more than one program uses the routines in the shared libraries. During linking, they do not require any special precautions to avoid naming conflicts with library routines. They might perform better than statically linked programs if several programs use the same shared routines at the same time. By using dynamic linking, you can upgrade the routines in the shared libraries without relinking. This form of linking is the default and no additional options are needed.

Static linking means that the code for all routines called by your program becomes part of the executable file. Statically linked programs can be moved to run on systems without the XL Fortran runtime libraries. They might perform better than dynamically linked programs if they make many calls to library routines or call many small routines. They do require some precautions in choosing names for data objects and routines in the program if you want to avoid naming conflicts with library routines.