I assume that there are more levels to outlet than reg, so the volume of output is higher. If you are running SAS interactively, it tries to store all of the log and output in memory and that is why you are getting the message. Dropping the notes saves some space. For a more robust solution, you can either
-- run in batch, as previously mentioned.
-- Use PROC PRINTTO to redirect the output to a file.
These are both limited by available disk space.