HTTPFileCache ever actually used?

[dblodgett-usgs]

Running TDS5 latest, I'm working on getting all our datasets to return under our 60 second time out limit. I have some large union aggregations that are taking too long to initialize. I can get them to work once but the next time I come around scanning all the end points in the catalog, they take too long again!

There is an element in threddsConfig.xml

  <!--
  The <HTTPFileCache> element:
  allow 10 - 20 open datasets, cleanup every 17 minutes
  used by HTTP Range requests.
  -->
  <HTTPFileCache>
    <minFiles>10</minFiles>
    <maxFiles>20</maxFiles>
    <scour>17 min</scour>
  </HTTPFileCache>

Does this actually get used anywhere? Searching around the code it doesn't appear to. What can I do to keep these unions fresh so just pulling back the .dds/.das is quick?