I am running a simulation with a stop time of 20 ks  (That's right kiloseconds) to model a process that can take minutes or hours.  However, there seems to be an upper limit on the length of a Cadence AMS simulation.  It gives me the following error whenever it encounters a simulation time beyond 2^63 fs.

Error!   simulated time overflow
             File:  ./ihnl/<proj>/<cell>/verilogams/verilog.vams, line = 67, pos = 1
             Scope:  <testbench>.I0
             Time:   9223372036 US + 0

You can tell here my precision is set to 1us, but I get the same error whenever I try to exceed 9.22 ks no matter what precision I choose with the `timescale directive.  

Maybe it stores values for time in terms of femptoseconds, and it's choking on too big an exponent.  It seems like there should be a way to change the base time unit.

Any ideas?