DECLARE
  vString ta_config_bigvalue.config_context%type;
BEGIN
  vString := '...8000个字符.....';

INSERT INTO lscm_ta_config_bigvalue
  (id,
   config_code,
   config_desc,
   create_tm,
   create_emp,
   update_tm,
   update_emp,
   config_context)
VALUES
  (1,
   'xxxxxx',
   '说明',
   to_date('26-06-2013', 'dd-mm-yyyy'),
   'xxx',
   to_date('26-06-2013', 'dd-mm-yyyy'),
   'xxxx',
   vString);

用变量即可.