The question is, which integer limits do you mean? The suggested POSIX INT_MAX and INT_MIN, and $Config {intsize}
gives information about the native integers of your system.
But that's not necessarely the same as the integer range
of your Perl! If you build your Perl to have 64 bit integers
POSIX::INT_MAX might still be 2147483647 and $Config {intsize} be 4. But then Perl is using longlongs as integers, and you
should be looking at $Config {longlongsize}.