[Kjaer]

^ What he said, you use the + to signify that you are about to define a variable in the startup line before the game loads, so you do not need this in server.cfg.

If you are going to set your mapcycle file in the cmd startup line that is fine (and probably the best way to do it), but if you are going to do in through config (.cfg) files, I would suggest adding it to the autoexec.cfg, and not server.cfg to ensure proper loading.