Resize DOS Memory Block

Changes the size of a memory block that was previously al
located with the Allocate DOS Memory Block function (Int 31H
Function 0100H).

Call With:

   AX     = 0102H
   BX     = new block size in (16-byte) paragraphs
   DX     = selector of block to modify

Returns:

   if function successful
   Carry flag= clear

   if function unsuccessful
   Carry flag= set
   AX     = error code
           0007H   memory control blocks damaged (also
                   returned by DPMI 0.9 hosts).
           0008H   insufficient memory (also returned by
                   DPMI 0.9 hosts).
           0009H   incorrect memory segment specified (also
                   returned by DPMI 0.9 hosts).
           8011H   descriptor unavailable
           8022H   invalid selector
   BX     = maximum possible block size (paragraphs)

Notes:

o  Requests to increase the size of an existing DOS memory
   block may fail due to subsequent DOS memory block
   allocations causing fragmentation of DOS memory, or
   insufficient remaining DOS memory.  In addition, the
   function will fail if the block is growing past a 64 KB
   boundary and the next descriptor in the LDT is not
   available.
o  A request to decrease the size of a DOS memory block may
   cause some descriptors that were previously allocated to
   the block to be freed and the limit of the new last
   descriptor for the block to be changed.
o  Under a DPMI 1.0 host, any segment registers which
   contain a selector being modified are reloaded by this
   function and any segment registers which contain a
   selector being freed are zeroed by this function.
o  Client programs should never modify or free any
   descriptors allocated by this function.  The Free DOS
   Memory Block function (Int 31H Fn 0101H) will
   deallocate the descriptors automatically.
o  Refer to the rules for descriptor usage in Appendix D.