CREATE TABLE T1
 (T1_ID      INTEGER  NOT NULL,
  T1_PARAM1  INTEGER  NOT NULL
 );
CREATE SEQUENCE t1_seq AS INTEGER START WITH  1  INCREMENT BY  1 ;
CREATE TABLE T2
 (T2_ID     INTEGER  NOT NULL  GENERATED BY DEFAULT
    AS IDENTITY (START WITH  1 , INCREMENT BY  1 , CACHE  20 , MINVALUE  1 , MAXVALUE  2147483647 , NO CYCLE, NO ORDER),
  T1_ID     INTEGER  NOT NULL,
  T2_PARAM  INTEGER
 );

ALTER TABLE T1
  ADD CONSTRAINT SQL051026001353080 PRIMARY KEY
   (T1_ID
   );

ALTER TABLE T2
  ADD CONSTRAINT SQL051026001419220 PRIMARY KEY
   (T2_ID
   );

ALTER TABLE T2
  ADD CONSTRAINT SQL051026001419300 FOREIGN KEY
   (T1_ID
   )
    REFERENCES T1
     (T1_ID
     )
    ON DELETE NO ACTION
    ON UPDATE NO ACTION
    ENFORCED
    ENABLE QUERY OPTIMIZATION;

t1_id | t1_param   t2_id  |  t1_id  |  t2_param
------+---------   -------+---------+----------
1     | 5            1    |  1      |  4
                     2    |  1      |  5
                     3    |  1      |  6

CREATE PROCEDURE PROC_INSERT
 (OUT P_T1_ID INTEGER, 
  IN P_T1_PARAM INTEGER, 
  IN P_T2_PARAMS VARCHAR( 1024 )
 ) 
  SPECIFIC PROC_INSERT
  LANGUAGE SQL
  NOT DETERMINISTIC
  CALLED ON NULL INPUT
  MODIFIES SQL DATA
  INHERIT SPECIAL REGISTERS

  p1: begin

  VALUES NEXTVAL FOR t1_seq INTO p_t1_id;
  INSERT INTO t1 (t1_id, t1_param) VALUES (p_t1_id, p_t1_param);

  -- что делать далее я не знаю, предполагал, что P_T2_PARAMS
-- будет строка вида '4, 5, 6', чтобы внутри процедуры получить 
-- with tmp (t2_param) AS (values ' || p_t2_params || ' ) 
-- select * from tmp и как-то сделать инсерт в таблицу T2.

 end p1;

insert into t2 (t2_param, t1_id) 
with tmp (t2_param) AS (values  365 ,  366 ,  367 ) select tmp.*,  1  AS t1_id from tmp;