Constant solana_runtime::block_cost_limits::MAX_BLOCK_UNITS

pub const MAX_BLOCK_UNITS: u64 = MAX_BLOCK_REPLAY_TIME_US * COMPUTE_UNIT_TO_US_RATIO * MAX_CONCURRENCY; // 0x0000_0000_0989_6800u64

Statically computed data:

Number of compute units that a block is allowed. A block’s compute units are accumualted by Transactions added to it; A transaction’s compute units are calculated by cost_model, based on transaction’s signarures, write locks, data size and built-in and BPF instructinos.