Function or hook for creating new menu_custom

If I was looking correctly, there is no any function which provides functionality to add new custom tree menu (menu_custom table).
system_update_6021() is creating tree directly in database and there is only menu_edit_menu_submit($form, &$form_state)
I'm not sure how is in 7.x, but there should be some function which can create new three menu or even the whole tree from the array (similar to hook_menu).
Is there any issue with providing this functionality?