Using php5 with gdbm

PHP5 is satisfactorily installed. However 'phpinfo()' returns the following (in the DBA section) DBAsupport => enabled Supported handles => cdb cdb_make inifile flatfile dba.default_handler => flatfile => flatfile dba_open("" file "", 'c', 'flatfile'); works as expected. However I want to use 'gdbm' (also installed). What do I have to do to get PHP to cooperate with string handler 'gdbm'? Your help will be much appreciated. Alan Fry