I'm reading Mafia: Last Secrets from Bill Bonanno at the moment..

He talks about all the Commission meetings in history he and his father attended. The 1956 meeting at Joe Barbera's house, the year before the notorious '57 one, was the first Bill himself attended he said.

He explains that there was a big fight between Giancana and Anastasia, because Giancana (at his first Commission meeting allegedly) said: ''When are you gonna kill Frank Scalise?''
Anastasia went beserk according to Bill and needed to be calmed down by his father Joe, the chairman of the meeting..

Bill explains that the remark was about the supposed button-selling racket, but I find it very strange that a guy like Giancana, not from NY and his first Commission meeting would challenge someone like Anastasia like that. But on the other hand, why would Bill lie about such a thing because in this case there's nothing to gain by it..