You may have seen this missing in your status report. I have finally gotten around to installing this. there are a few things that I had to do.
this is a great link. read it. there is a lot of confusion because drupal tells you you need it but doesn’t really tell you how to enable it. that’s because it is really a function of the os. but the link will tell you what to do.
this is another good link on PECL.