Like previous versions of OS X, 10.9 also ships with PEAR. To install and activate it, a few steps are necessary. After that PEAR and PECL work as expected (if you also want to set up and install Apache, PHP and MySQL, check this Gist.
cd /usr/lib/php
sudo php install-pear-nozlib.phar
autoconf may be missing. To install it just use Homebrew. Once Homebrew is installed, installing autoconf is as simple as:
brew install autoconf
After autoconf is installed, try running the pear installer above again.
sudo pear channel-update pear.php.net
sudo pecl channel-update pecl.php.net
sudo pear upgrade-all
You will run into problems installing pecl extensions, if you don't have the Xcode Command Line Extensions installed, so we'll also install them.
xcode-select --install
Open /etc/php.ini and add ".:/usr/lib/php/pear" to include_path (if /etc/php.ini does not exist, create it with the following contents).
include_path = ".:/usr/lib/php/pear"