RPTR STATES THAT NO ADVISORY WAS GIVEN ABOUT ACFT Y THAT DEPARTED ON THE PARALLEL RWY.

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I AM NOT CERTAIN IF THIS SIT IS AN ABNORMAL OCCURRENCE SINCE I AM NOT FAMILIAR WITH ATC SEPARATION REQUIREMENTS ON PARALLEL RWY OPS. WE WERE CLRED FOR TKOF FROM BOS RWY 4L. NO DEP HDG WAS ASSIGNED SO RWY HDG WAS MAINTAINED PER OUR LOGAN 2 CLRNC. AFTER THE GEAR WAS RAISED; BOTH THE FO AND I NOTICED OUR TCASII WAS DISPLAYING PROX TFC AT OUR ALT AND OUR POS. I BEGAN A VISUAL SEARCH WHEN THE FO SAID THE TFC WAS ON HIS SIDE. I LOOKED; AND AT OUR 3 O'CLOCK POS WAS A B767 CLBING PARALLEL TO US. TWR HAD ALREADY HANDED US OFF TO DEP AND THEY WERE TALKING TO OTHER TFC. SO WE WERE UNABLE TO IMMEDIATELY GET A TURN AWAY. THE B767 WAS AS FAR FROM US AS THE DISTANCE BTWN RWYS 4L&R AT BOS. I MAINTAINED MY HDG; HE MAINTAINED HIS; UNTIL DEP CLRED US FOR A L TURN (AT APPROX 2000 FT). JUST AS I SAID IN THE BEGINNING OF THIS RPT; I DON'T KNOW IF THIS WAS A PROB. WE HAD NO WARNING ABOUT ACR AND IT WAS UNNERVING SEEING A PLANE THAT CLOSE WITHOUT ANY WARNING FROM ATC. THE REST OF THE FLT CONTINUED WITHOUT INCIDENT. I FEEL ATC SHOULD HAVE EITHER GAVE US A HDG ON DEP; TOLD US THE OTHER PLANE WAS GOING TO BE THERE; OR STAGGERED THE DEPS SO EITHER ONE OF US WAS AHEAD OF THE OTHER. WE WERE DEFINITELY DISTR FROM OUR DUTIES DURING A CRITICAL PHASE OF FLT.