Constant solana_sdk::syscalls::MAX_CPI_ACCOUNT_INFOS

pub const MAX_CPI_ACCOUNT_INFOS: usize = 64; // 64usize

Maximum number of account info structs that can be used in a single CPI invocation. A limit on account info structs is effectively the same as limiting the number of unique accounts. 64 was chosen to match the max number of locked accounts per transaction (MAX_TX_ACCOUNT_LOCKS).