Get/set memory allocation strategy (INT 21h, 58h)

        Entry:
          AH = 58h
          AL = function code
                  0 = get allocation strategy
                  1 = set allocation strategy
                     BL = strategy code
                         0 first fit (use first memory block large enough)
                         1 best fit (use smallest memory block large enough)
                         2 last fit (use high part of last usable memory
                           block)
        Return:
          CF = 1 error
                  AX = Error Code
          CF = 0 successful
                  AX = strategy code

        Note: The Set subfunction accepts any value in BL; 2 or greater
              means last fit. The Get subfunction returns the last value
              set, so programs should check whether the value is >= 2, not
              just equal to 2.