From Mirc Help file:
/sockread [-fn] [numbytes] <%var|&binvar>
If you specify a &binvar then [numbytes] of info is read into the binary variable. If no [numbytes] is specified it defaults to 4096 bytes.
So you can make it all in one read, if the socket has all the data stored already
I think you misunderstood what I asked.
It's not about a default but about a limit.
I'll put it another way:
Does /sockread -f 8192 &somebinvar make sense or not?
Because if /sockread cannot read more than 4k in one time, then it doesnt make sense.