#include <db.h> int db_env_create(DB_ENV **dbenvp, u_int32_t flags);
        The db_env_create() function creates a DB_ENV 
        structure that is the handle for a Berkeley DB environment. This function allocates memory for the structure,
        returning a pointer to the structure in the memory to which 
        dbenvp refers. To release the allocated memory and discard the
        handle, call the 
        DB_ENV->close() or 
        DB_ENV->remove() methods.
    
        DB_ENV handles are free-threaded if the 
        DB_THREAD flag is specified to the
        DB_ENV->open() method when the environment is opened.
        The DB_ENV handle should not be closed while any other handle
        remains open that is using it as a reference (for example, 
        DB or DB_TXN). 
        Once either the
        DB_ENV->close() or 
        DB_ENV->remove() 
        methods are called, the handle may not be accessed again, regardless of the method's return.
    
Before the handle may be used, you must open it using the DB_ENV->open() method.
            The DB_ENV handle contains a special field, app_private, which is declared as type 
            void *. This field is
            provided for the use of the application program. It is initialized to NULL and is not further used by
            Berkeley DB in any way.
    
        The db_env_create() method returns a non-zero error value on failure and 0 on success. 
    
The flags parameter must be set to 0.