I believe the Batman monthly is the first series to reach the 100 issue mark since the New 52 started. I'm referring to reaching a 100th issue in its numbering, without being rebooted, cancelled/restarted or legacy numbering brought back.
Crazy to think its been over 9 years since we've seen a monthly have a 3 digit issue count on the cover (besides Action and Detective) in the DCU monthlies.