appthemes_before_page_comments

This function executes in the comments-page.php file and runs before the comments template is loaded.

appthemes_before_page_comments();

You can use this hook to add meta data to a page, like a share link for social media sites.

<?php
function insert_share_link() { 
    echo '<div class="share-link">' . __( 'Share this link with your friends!', 'appthemes' ) . '<input type="text" value="' . esc_attr( get_permalink() ) . '">';
} 
add_action( 'appthemes_before_page_comments', 'insert_share_link' ); 
?>