What is the biggest high school in Philippines?

As of my most recent knowledge update in September 2021, the biggest high school in the Philippines is the Caloocan National High School, located in the city of Caloocan in Metro Manila. However, it's possible that there have been changes or new high schools that may have surpassed Caloocan National High School in terms of student population or campus size since then. To ensure the most accurate and up-to-date information, I recommend checking the latest official rankings or statistics provided by the Department of Education in the Philippines.