Operating systems limit how many files are opened *at a time*, but they don't limit how many files a process can open over its lifetime.

I don't see anything that would cause your problem, but I do have issues.

• Use lexical file handles. It will ensure they get cleaned up and closed even if the subroutine exits abnormally.

• What is open(STDIN, "-");? - means STDIN, so you're opening STDIN to be the same as STDIN?!

• Also, calling dealError from within dealError is problematic.

• Finally, what is dealError trying to do? Short of a missing floppy in the drive, I don't know of an error that can be "checked" and fixed.

I'd recommend:

sub proc{
    my ($file) = @_;
    # (...)
    my $pathC = $path . "/$file";
    open my $input, "zcat $pathC|"
        or do {
            print STDERR "\n!!ATTENTION:\n\tUnable to run zcat: $!\n";
            return;
        };

    while (my $line = <$input> ){
        # (...) data proccessing irrelevant to the problem
    }

    # Not needed. Will happen automatically
    # when $input goes out of scope.
    #close($input);
}
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