INT 21 - DOS 3+ - GET OR SET MEMORY ALLOCATION STRATEGY
        AH = 58h
        AL = subfunction
            00h get allocation strategy
                Return: AX = current strategy
                            00h low memory first fit
                            01h low memory best fit
                            02h low memory last fit
                         ---DOS 5+ ---
                            40h high memory first fit
                            41h high memory best fit
                            42h high memory last fit
                            80h first fit, try high then low memory
                            81h best fit, try high then low memory
                            82h last fit, try high then low memory
            01h set allocation strategy
                BL = new allocation strategy (see above)
                BH = 00h (DOS 5+)
Return: CF clear if successful
        CF set on error
            AX = error code (01h) (see AH=59h)
Notes:  the Set subfunction accepts any value in BL for DOS 3.x and 4.x;
          2 or greater means last fit
        the Get subfunction returns the last value set
        setting an allocation strategy involving high memory does not
          automatically link in the UMB memory chain; this must be done
          explicitly with AX=5803h in order to actually allocate high memory
        a program which changes the allocation strategy should restore it
          before terminating
        Toshiba MS-DOS 2.11 supports subfunctions 00h and 01h
        DR-DOS 3.41 reportedly reverses subfunctions 00h and 01h
SeeAlso: AH=48h,AH=49h,AH=4Ah,INT 2F/AX=4310h,INT 67/AH=3Fh

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