MS DOS overlay programming

No they can't. ;) These techniques are of use on a lot of small memory machines with rudimentary operating systems. Sorry, have 5 minutes of spare time so I'm catching up on topics in reverse order. Are you putting the TCP/IP stack in a TSR (and want to reduce memory there). Or is it the application that you are trying to reduce memory use in? If the application, is it a .com file or a .exe? I think an overlay manager is overkill. The general way I handled such things (in the distant past, when I had time to do such fun things) was.... If using a TSR or .COM file, place the initialization code after the data section used by the initialization, feeling free to overwrite the initialization code with data (.COM) or free the initialization code. As long as you have your initialization variables in a static section below the initialization code it's pretty easy. It's a little bit more difficult in a .EXE file, since there is (potentially) OS interaction with heap allocation. Methods I have used are: 1) copying the initialization code to the top of the heap prior to execution and storing the initialization data on top of the code that was copied. 2) writing my own memory allocation code using a static variable as a heap, and changing the link order to insure the initialization code ends up above this variable. 3) manually modifying the heap pointers to "free" the initialization routines. I'm sure there are other methods that I'm not thinking of, since this was such a common problem. Eric