Hello @FVidal,
its usage should be tracked within the SAS metadata server and within the SAS Forecast Studio web application.
On one side, it might be possible that you will need to extend the information on logs to higher levels (DEBUG is the highest) or to include additional java components to be logged. If you know about Log4J you will know what I mean.
In the other side, you will of course need to locate the log's location and the configuration files for those logs.
For the first question, I reccommend the reading of:
Problem Note 58601: Enabling middle-tier debugging in SAS® Model Manager: http://support.sas.com/kb/58/601.html This note is for Model Manager but the procedure would be very similar for Forecast Studio
Enable More Detailed Logging for Server Troubleshooting: http://support.sas.com/documentation/cdl/en/bisag/68240/HTML/default/viewer.htm#p0hchigzq8wvtrn1tnll...
For the second question:
Default Locations for Server Logs: http://support.sas.com/documentation/cdl/en/bisag/68240/HTML/default/viewer.htm#p1ausbmrrybuynn1xnxb...
Usage Note 55426: Locating the log files for the SAS® 9.4 middle tier: http://support.sas.com/kb/55/426.html
And as general information, only for the moment you will have some spare time: http://support.sas.com/documentation/cdl/en/logug/67485/PDF/default/logug.pdf
Hope it helps.
Good luck! / Suerte!
Juan