Is the 1000 block retention configurable in algod?

From here:

Non-Archival nodes will delete old blocks and only retain what’s need to properly validate blockchain messages (currently the last 1000 blocks).

Is this configurable? I’d like to be able to query my algod from blocks 18M onwards. My idea was to give it a catch to a ~18M catchpoint and then change it into archival, but this makes it start over from zero. If I could configure this to value be 999999999 instead of 1000 I would accomplish what I’m after.