You are viewing the version of this documentation from Perl blead. This is the main development branch of Perl. (git commit 55c5b505cb6ecaf868f1326432801de3a67c9943)
listen SOCKET,QUEUESIZE

Does the same thing that the listen(2) system call does. Returns true if it succeeded, false otherwise. See the example in "Sockets: Client/Server Communication" in perlipc.