That's not a valid option, and it's not a valid DBCC command either.
CheckDB checks are by default online, there's nothing you need to add to ensure that. They can slow things down, but they won't take the DB offline.
DBCC CHECKTABLE (<Table Name>) WITH NO_INFOMSGS, ALL_ERRORMSGS
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
We walk in the dark places no others will enter
We stand on the bridge and no one may pass