Tiny memory model .COMs get all the memory, which can be less
or more than 64KB. I simply resize the block to 64KB and move SP
to its end (if the resizing fails, the .COM terminates with error).
The library manages the heap space between the static
variables and the stack.
My small memory model .EXEs don't resize anything as they
always get the minimum specified in the header, which is
set to a value that guarantees a full 64KB data/stack segment.
The library manages the heap space the same way.
Alex