Equivalent to header('X-Accel-Buffering: no') in Openlitespeed to disable output buffering?

Hello, i am moving from NGINX to Openlitespeed. On NGINX to stream a file (php readfile()) i could use header('X-Accel-Buffering: no'); to disable output buffering. How would i do this on Openlitespeed? is there a setting or a special header? Any help is appreciated.