Constant MAX_SEND_WINDOW 

pub const MAX_SEND_WINDOW: u32 = _; // 524_288u32

Available on crate feature std only.

Hard ceiling on the credit-based send window. WINDOW_UPDATE frames add relative credit; this caps the accumulated window so a peer that floods inflated credits cannot overflow the counter. A compliant peer never grants more than ~one INITIAL_STREAM_WINDOW of outstanding credit, so the cap is only a misbehaving-peer guard (the receiver’s own delivery HARD_CAP is the real bound on buffering).