%VAL (arg)

  Forces an actual argument in a CALL statement or function reference
  to be passed by value.  The argument is passed as a 64-bit immediate
  value.  If "arg" is integer (or logical) and less than 64 bits in
  size, it is sign-extended to a 64-bit value.

  When a complex argument is passed, two 64-bit values (one containing
  the real part, the other containing the imaginary part) are passed
  by immediate value.