100% height of columns in bootstrap panel

how can I get 100% of height for all three columns without content?

here's a jsfiddle:

    <div class="row">
  <div class="col-md-12">
    <div class="shadow panel panel-default">
      <div class="blue white-border panel-heading">
        <h3 class="panel-title text-white">
          Contacts
        </h3>
      </div>
      <div class="panel-body">
        <div class="col-xs-3 green">1</div>
        <div class="col-xs-3 red">2</div>
        <div class="col-xs-6 black">3</div>
      </div>
    </div>
  </div>
</div>

http://ift.tt/1EBdwQo