Three is no need to use proprietary procedural code to pass a list of 
parameters to a stored procedure.  It can be done by putting them into 
a string with a separator.  I like to use the traditional comma.  
Let's assume that you have a whole table full of such parameter lists:

CREATE TABLE InputStrings
(keycol CHAR(10) NOT NULL PRIMARY KEY,
 input_string VARCHAR(255) NOT NULL);

INSERT INTO InputStrings VALUES ('first', '12,34,567,896');
INSERT INTO InputStrings VALUES ('second', '312,534,997,896');
 ...

This will be the table that gets the outputs, in the form of the original 
key column and one parameter per row.

CREATE TABLE Parmlist
(keycol CHAR(5) NOT NULL PRIMARY KEY,
 parm INTEGER NOT NULL);

It makes life easier if the lists in the input strings start and end 
with a comma.  You will need a table of sequential numbers -- a standard 
SQL programming trick,  Now, the real query:

INSERT INTO ParmList (keycol, parmlist)
SELECT keycol,
       CAST (SUBSTRING (I1.input_string
                        FROM S1.seq +1
                         FOR MIN(S2.seq) - S1.seq -1)
         AS INTEGER)
  FROM InputStrings AS I1 ,  Sequence AS S1 , Sequence AS S2
 WHERE SUBSTRING (‘,’ || I1.input_string || ‘,’ FROM S1.seq FOR 1) = ‘,’
   AND SUBSTRING (‘,’ || I1.input_string || ‘,’ FROM S2.seq FOR 1) = ‘,’
   AND S1.seq < S2.seq
 GROUP BY I1.keycol, I1.input_string, S1.seq;

The S1 and S2 copies of Sequence are used to locate bracketing pairs of 
commas, and the entire set of substrings located between them is 
extracts and cast as integers in one non-procedural step.  The trick 
is to be sure that the right hand comma of the bracketing pair is the 
closest one to the first comma.

You can then write:

 SELECT *
   FROM Foobar
  WHERE x IN (SELECT parm FROM Parmlist WHERE key_col = :something);