Resize Memory Block


                 This function  changes the  size of a memory block that
                 was  allocated   through  the   allocate  memory  block
                 function.

            To Call

                 AX = 0503h
                 BX:CX = New size of memory block to allocate in bytes
                 SI:DI = Handle of memory block to resize

            Returns

                 If function was successful:
                 Carry flag is clear
                 BX:CX = New linear address of memory block
                 SI:DI = New handle of memory block

                 If function was unsuccessful:
                 Carry flag is set

            Programmer's Notes

                 o    This function may change the linear address of the
                      memory block  and the  memory handle.   Therefore,
                      you will  need to  update any selectors that point
                      to the  block after resizing it.  You must use the
                      new handle instead of the old one.
                 o    This function  will generate  an error if a memory
                      block is resized to 0 bytes.