Trumpet's product was popular, as it provided a winsock (Windows sockets) interface as well as a TCP/IP stack, but it was only one of many soluttions available. FTP Software's PC/TCP, Novell's LAN Workplace (and later, the NetWare client), and Microsoft's own TCP/IP stack were also popular solutions. I believe Banyan sold an IP stack as well.
Bascially, you used whatever protocols came with your NOS of choice (Vines, NetWare, LAN Manager, OS/2, some variant of UNIX, etc.), and sometimes, one of those protocols was TCP/IP. Most businesses running something other than UNIX didn't start migrating to TCP/IP until the mid to late 90's. Hell, the [extremely large and well-known] bank I work for didn't standardize on TCP/IP until 2003. ('Cause before then it was Red (Novell) vs. Blue (IBM)).
The word `stack' is used to describe any set of layered protocols, because, you know, they're like stacked one on top of the other. :-P
Trev