Currently the policy is having a limitation of maximum of 3600 seconds (1 hour) as the HTTP Server Receive Timeout. If any higher value is set, you will be presented with an error similar to the one following:
     <proxy>
  url.address=x.x.x.x http.server.recv.timeout(3601)

  Error: The value was outside the valid range: '3601' -- valid range is 1 to 3600

This limitation occurs only when the receive timeout is called via a policy. The global setting can have values more than 3600. Commands for adding the global setting is given below

   Enable
 
   Config t
 
   http receive-timeout server xxx


Note: This change is a “Global” one. For anything less than one hour, try to use the policy itself.