FIREConfigFiles is an option for FIREBurn.
It specifies, where the three files that contain all the FIRE
configuration are saved.
The first file contains the lists of loop momenta, external momenta
and propagators. Normally it ends with the FIRE command
SaveStart.
The second file loads the .start file that was generated previously and reduces the given loop integrals.
Finally, the third file contains replacement rules for the introduced
abbreviations. The default location of these files is the
Database folder inside $FeynCalcDirectory.