You should really use an external syslog server. Even the free version of Solarwinds' Kiwi syslog server is useful.
Since the local log buffer will quickly fill up for the more verbose log messages like Notification and Informational, I recommend setting local logging to a relatively high priority level - i.e. warning and higher severity and increasing the defualt buffer size. Only use the more verbose levels when troubleshooting. Do not turn on "logging console" unless you are sitting at the console using it in real time. Otherwise is consumes unnecessary resources.
Something like this:
logging enable
logging timestamp
logging buffer-size 100000
logging asdm-buffer-size 512
logging buffered warnings
FYI here are the levels:
Alert Messages, Severity 1
Critical Messages, Severity 2
Error Messages, Severity 3
Warning Messages, Severity 4
Notification Messages, Severity 5
Informational Messages, Severity 6
Debugging Messages, Severity 7
