The only journal entry needed for a stock split is a memo entry to note that the number of shares has changed and that the par value per share has changed (if the stock has a par value). However, a typical journal entry with debits and credits is not needed since the total dollar amounts for the par value and other components of paid-in capital and stockholders' equity do not change.
For example, if a corporation has 100,000 shares of $1.00 par value stock and it declares a 2-for-1 stock split, the corporation will have 200,000 shares with a par value of $0.50 per share. Before and after the stock split, the total par value is $100,000. Other account balances within stockholders' equity also remain the same.