1.DBG> CALL SUB1(X)
      value returned is 19
      DBG>

      This command calls routine SUB1, with parameter X (by default,
      the address of X is passed). In this case, the routine returns
      the value 19.

    2.DBG> CALL SUB(%REF 1)
      value returned is 1
      DBG>

      This command passes a pointer to a memory location containing
      the numeric literal 1, into the routine SUB.

    3.DBG> SET MODULE SHARE$LIBRTL
      DBG> CALL LIB$SHOW_VM
       1785 calls to LIB$GET_VM, 284 calls to LIB$FREE_VM, 122216 bytes
       still allocated, value returned is 00000001
      DBG>

      This example calls Run-Time Library routine LIB$SHOW_VM
      (in shareable image LIBRTL) to display memory statistics.
      The SET MODULE command makes the universal symbols (routine
      names) in LIBRTL visible in the main image. See also the SHOW
      MODULE/SHARE command.

    4.DBG> CALL testsub (%val 11.11, %val 22.22, %val 33.33)

      This example passes floating-point parameters by value, to a
      C subroutine with the function prototype void testsub (float,
      float, float). The floating-point parameters are passed in F_
      floating format.