Function 31h (49)        Terminate and Stay Resident

    Terminates a process, but keeps a specified portion resident in
    memory.

       On entry:      AH         31h
                      AL         Return code
                      DX         Size of resident portion, in paragraphs

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    Function 31h is an enhanced version of DOS Interrupt 27h, Terminate
    and Stay Resident, that offers two extra features: It allows more than
    64K of memory to remain resident, and allows the terminating process
    to report a return code.

       Notes:         This function does not release any memory that was
                      allocated by the terminating process via Function
                      48h (Allocate Memory).

                      The return code may be retrieved by a parent process
                      via Function 4Dh, or tested by means of the
                      ERRORLEVEL feature of DOS batch processing.

                      Open files are not closed by this function.