In C, dynamic calls are made by invoking the fetch() function and then later invoking the fetched routine with the returned fetch pointer. The fetched routine can either be a C or Fortran routine: the C routine can then fetch or statically call a Fortran routine; the Fortran routine can then statically call a C routine. (If the statically linked C routine is within a dynamically loaded module with a Fortran entry point, the C routine must be either nonreentrant or naturally reentrant.) In the fetched load module, a routine can dynamically call other C or Fortran routines, regardless of whether the routines are reentrant.

A C routine that fetches a Fortran routine cannot contain a fork() function. Although you cannot run an application with fork(), you can run with POSIX(ON). For a full description of running under POSIX, see z/OS Language Environment Programming Guide.