`backlog` parameter

[Lintkey]

In src\os\unix\listener.rs:88~92

        // FIXME the standard library uses 128 here without an option to change this
        // number, why? If std has solid reasons to do this, remove this notice and
        // document the method's behavior on this matter explicitly; otherwise, add
        // an option to change this value.
        c_wrappers::listen(&fd, 128)?;

The size of the accept queue is equal to min(SOMAXCONN, backlog), by default SOMAXCONN=128.

SOMAXCONN: socket max connections, man page.