#include <db.h>

int
DB->set_heap_regionsize(DB *db, u_int32_t npages);  

Sets the number of pages in a region of a database configured to use the Heap access method. If this method is never called, the default region size for the database's page size will be used. You can set the database page size using the DB->set_pagesize() method.

The DB->set_heap_regionsize() method may not be called after the DB->open() method is called. If the database already exists when DB->open() is called, the information specified to DB->set_heap_regionsize() will be ignored. If the specified region size is larger than the maximum region size for the database's page size, an error will be returned when DB->open() is called. The maximum allowable region size will be included in the error message.

The DB->set_heap_regionsize() method returns a non-zero error value on failure and 0 on success.