...

CONFIG proxy.config.http.background_fill_completed_threshold FLOAT 1.000000

HTTP VARY Header Support

While I found some information while researching this that indicated the Internet isn't quite ready for this
setting, I haven't experienced any real problems as a result of enabling this. This setting allows for advanced
negotiation regarding cached Internet objects.

CONFIG proxy.config.http.cache.enable_default_vary_headers INT 1

Cache Object Lifespan

The default config for ATS specifies that after 1 day(86,400 seconds), any object without a specific expiration
should be flushed from the cache. I'd prefer that it stick around for about 3 months. This setting is contentious
in that what it should be is debatable.

...