WordPress at a glance
action is not described

wp_creating_autosave action-hook . WP 4.1.0

Fires before an autosave is stored.

Usage

add_action( 'wp_creating_autosave', 'action_function_name_3221' );
function action_function_name_3221( $new_autosave ){
	// action...
}
$new_autosave(array)
Post array - the autosave that is about to be saved.

Where the hook is called

wp_create_post_autosave()
wp_creating_autosave
WP_REST_Autosaves_Controller::create_post_autosave()
wp_creating_autosave
wp-admin/includes/post.php 1741
do_action( 'wp_creating_autosave', $new_autosave );
wp-includes/rest-api/endpoints/class-wp-rest-autosaves-controller.php 358
do_action( 'wp_creating_autosave', $new_autosave );

Where the hook is used (in WP core)

Does not used.