You remove block <block type="catalog/product_view">
from custom layout.As As per magento system any function value set and child blocks assign of a block class can be managed using any function value set and child blocks assign of a block class can be managed using <reference> tag
tag
<reference name="product.info.addtocart">
<action method="setData">
<name>in_stock_text</name>
<value>This product is in stock.</value>
</action>
</reference>
You can study about layout