The upload configuration has changed between 4.0 and 4.5. In aolserver 4.5, the command ns_limits is used to change various settings.
To get the defaults, use the command (e.g. from ds/shell)
ns_limits get default
and you get
nrunning 1 nwaiting 0 ntimeout 0 ndropped 0 noverflow 0 maxwait 100 maxupload 10240000 timeout 60 maxrun 100
The file upload limit can be altered to e.g. twice the size (about 20MB) by
ns_limits set default -maxupload 20480000
This command can be written as well to the config-file