If you are on Windows, this might be helpful:
http://support.microsoft.com/kb/830473
The max command length is 8191 chars on Win XP or 4191 on Win 2K.
BUT in order to get that max limit, you must have an environment size that allows it.
This might be helpful:
http://msdn.microsoft.com/en-us/library/ms682653(VS.85).aspx

If you are a *NIX platform there are similar limits.

There are reasons to have large command lines when working with various utilities and when using a large number of pipe commands. But this definitely not a Perl limitation. Personally when something like this: >proga ....parms.. | progr B .... | prog c ... gets more than a couple of lines, I split it up and use temp files. Normally these very lengthy things are shell commands. I don't know why your Perl program would have to deal with such a thing.

Update: I've never seen a limit as low as 257 on a modern O/S. All of these things can do more, it sounds like a configuration problem to me.