How to retrive Category name from menu

Hello i have some complex theme , i have some other custom pages for specific category list because i need to list them different :

<?php if ( have_posts() ) : ?>

                <div id="blog-grid" class="row content-grid">
                <?php 
                query_posts('category_name=catname1&showposts=20');
                while ( have_posts() ) : the_post();
                ?>
                    <div class="<?php echo esc_attr( tdmacro_column_class() ); ?> post-box">
                    <?php get_template_part( 'content', get_post_format() ); ?>
                    </div><!-- .col -->
                <?php endwhile; ?>
                </div><!-- .row -->

                <?php tdmacro_paging_nav(); ?>

            <?php else : ?>

                <?php get_template_part( 'content', 'none' ); ?>

            <?php endif; ?>

You can see this line :

query_posts('category_name=catname1&showposts=20');

which i using to take the specific category post name lists.

Now lets see i put subpage under catname1 with the same custom template and call him catname2, i want to pull from menu when i press catname2 and list all posts from catname2 it's possible ?

i mean to change this query_posts('category_name=catname1&showposts=20'); by specific cat name each time on change .

Now it's not dynamic it's only show catname1 posts .

I try :

 $cat_mame = get_cat_name( $currentcatID ) ;

and more method from google/wordpress codex but didn't get it to work, thanks.