This -b argument was in /var/lib/aolserver/service0/etc/daemontools/run but I did not remove the commented line above it. This caused it not to take the argument. Now it does.
But... there is a different problem now. When registering, users get a notification email stating they have registered in www.mysite.com:8000 instead of www.mysite.com. It did run on port 8000 for a short time, but I changed it. In config.tcl I have port 80 defined. I cannot find - within ACS - where to change this. Any help appreciated!