Hmm, I found this snippet of code, which can be found in the init sub in the raw CGI.pm you can download from there:

METHOD: {

      # avoid unreasonably large postings
      if (($POST_MAX > 0) && ($content_length > $POST_MAX)) {
      $self->cgi_error("413 Request entity too large");
      last METHOD;
      }
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So it's not as if the POST_MAX functionality has been stripped from CGI.pm 3.01 in all versions. Maybe there's a glitch in the tarball? (which I'm assuming you used).

I'd be interested to see what happens if the module is in fact *installed* rather than (as appears to have been the case here) just taking the CGI.pm file from the tarball and placing it in the same directory as the CGI script. After all, you gotta leave something for Makefile.PL to do =)

update : here's a thought. Try :

grep 'POST_MAX' *
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in the directory where you unpacked the tarball.

perl -e 'print "How sweet does a rose smell? "; chomp ($n = <STDIN>); 
+$rose = "smells sweet to degree $n"; *other_name = *rose; print "$oth
+er_name\n"'
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