Function solana_stake_program::stake_state::validate_split_amount

fn validate_split_amount(
    invoke_context: &InvokeContext<'_>,
    transaction_context: &TransactionContext,
    instruction_context: &InstructionContext,
    source_account_index: IndexOfAccount,
    destination_account_index: IndexOfAccount,
    lamports: u64,
    source_meta: &Meta,
    source_stake: Option<&Stake>,
    additional_required_lamports: u64
) -> Result<ValidatedSplitInfo, InstructionError>

Ensure the split amount is valid. This checks the source and destination accounts meet the minimum balance requirements, which is the rent exempt reserve plus the minimum stake delegation, and that the source account has enough lamports for the request split amount. If not, return an error.