What does the 'size of database' parameter do when creating a SQLite database?

When creating a SQLite database with javascript, there is a size of database parameter.

var db = openDatabase('mydb', '1.0', 'Test DB', 2 * 1024 * 1024);

• What does the size of database parameter do... does it limit the max size that the database can hold?

• What happens if you exceed that size?

• What is the max that number can be set at?