Sets or clears the default transaction of the calling process.

    $SET_DEFAULT_TRANSW always waits for the request to complete
    before returning to the caller. Other than this, it is identical
    to $SET_DEFAULT_TRANS.

    Format

      SYS$SET_DEFAULT_TRANSW  [efn] ,[flags] ,iosb [,[astadr]

                              ,[astprm] ,[new_tid] ,[old_tid]]

    C Prototype

      int sys$set_default_transw  (unsigned int efn, unsigned int

                                  flags, struct _iosb *iosb,...);