I just don't know how you can achieve that with static cache ... only if somebody else requested that exact mortgage calculation before and it is still in the cache.
Also, my idea of the "given input" from the earlier comment would have to include results of sql queries that would form the entire input to the LSTM.
But honestly I think over trained auto encoders can be used as hash maps. That would be an application more in line with what I think you are saying.