This example allocates SYS1.MACLIB to SYSLIB and directs messages to standard error (stderr):

    typedef int EXTF();
   #pragma linkage(EXTF,OS_UPSTACK)
   
   int call_alloc()
   {
   EXTF *bpxwdyn=(EXTF *)fetch("BPXWDYN");
   return bpxwdyn("alloc fi(syslib) da(sys1.maclib) shr msg(2)")
   }