Jython, DB2 and overloaded stored procedures

Problem
DB2 allows stored procedure overloading.

CREATE TABLE TMESSAGE (WHAT CHAR(1), MESS VARCHAR(200))@

CREATE OR REPLACE PROCEDURE PUTM (IN MESS VARCHAR(200))
P1: BEGIN
  INSERT INTO TMESSAGE VALUES('A',MESS);
END P1
@

CREATE OR REPLACE PROCEDURE PUTM (IN MESS1 VARCHAR(200), IN MESS2 VARCHAR(200))
P1: BEGIN
  INSERT INTO TMESSAGE VALUES('B',MESS1 || ' ' || MESS2);
END P1
@

CALL PUTM('Hello')@

CALL PUTM('Another hello','Wow')@

Jython,zxJDBC 
But if one tried to execute this procedure from jython a nasty message would appear (make sure that you have a db2 JDBC driver somewhere in the classpath)

from com.ziclix.python.sql import zxJDBC

url = "jdbc:db2://think:50004/SAMPLE"
driver = "com.ibm.db2.jcc.DB2Driver"
conn =  zxJDBC.connect(url, "db2inst2", "db2inst2", driver)
cur = conn.cursor()
cur.callproc('PUTM',['Hello'])
conn.commit()

   cur.callproc('PUTM',['Hello'])
zxJDBC.Error: error setting index [3], type [12] [SQLCode: 0]
DB2 SQL Error: SQLCODE=-440, SQLSTATE=42884, SQLERRMC=PUTM;PROCEDURE, DRIVER=4.15.82 [SQLCode: -440], [SQLState: 42884]
DB2 SQL Error: SQLCODE=-727, SQLSTATE=56098, SQLERRMC=2;-440;42884;PUTM|PROCEDURE, DRIVER=4.15.82 [SQLCode: -727], [SQLState: 56098]

To find a clue it is necessary to run 'procedurecolumns' method:

cur.procedurecolumns(None,'DB2INST2','PUTM',None)
for r in cur.fetchall():
     print r

(None, u'DB2INST2', u'PUTM', u'MESS', 1, 12, u'VARCHAR', 200, 200, None, None, 1, None, None, 12, None, 200, 1, u'YES', u'SQL130209104619000')
(None, u'DB2INST2', u'PUTM', u'MESS1', 1, 12, u'VARCHAR', 200, 200, None, None, 1, None, None, 12, None, 200, 1, u'YES', u'SQL130209104619400')
(None, u'DB2INST2', u'PUTM', u'MESS2', 1, 12, u'VARCHAR', 200, 200, None, None, 1, None, None, 12, None, 200, 2, u'YES', u'SQL130209104619400')

zxJDBC does not differentiate between parameters from overloaded procedures and takes the whole output from 'procedurecolumns' to make a prepared statement '{ call PUTM(?,?,?) }' which obviously does not match any procedure signature. In order to get it running zxJDBC should group parameters by the last column  SPECIFIC_NAME and match against number of parameters in 'callproc' method to prepare a valid function call.
Workaround 
The temporary solution is simply do not use 'callproc' method and use the call escape sequence directly.

query = '{ call PUTM(?) }'
cur.executemany(query,['Hello'])
query = '{ call PUTM(?, ?) }'
cur.executemany(query,['Hello with two','Wow'])

Jython, DB2 stored procedure and CLOB 
I run into another problem also.

CREATE PROCEDURE CALLCB (IN PARAM CLOB(2M))
P1: BEGIN
  INSERT INTO TMESSAGE VALUES('E',PARAM);
END P1

cur = conn.cursor()
cur.callproc('CALLCB',['Hello'])

I fails with the DB2 error message:

   cur.callproc('CALLCB',['Hello'])
zxJDBC.Error: DB2 SQL Error: SQLCODE=-301, SQLSTATE=07006, SQLERRMC=1, DRIVER=4.15.82 [SQLCode: -301], [SQLState: 07006]

It seems that zxJDBC does not map string to clob parameter correctly. But after applying zxJDBC enhancer it works as expected.

class PyHandler(DataHandler):
    def __init__(self, handler):
        self.handler = handler
#        print 'Inside DataHandler'
    def getPyObject(self, set, col, datatype):
        return self.handler.getPyObject(set, col, datatype)
    def getJDBCObject(self, object, datatype):
#        print "handling prepared statement"
        return self.handler.getJDBCObject(object, datatype)
    def preExecute(self, stmt):
#        print "calling pre-execute to alter behavior"
        return self.handler.preExecute(stmt)

cur = conn.cursor()
cur.datahandler = PyHandler(cur.datahandler)
cur.callproc('CALLCB',['Hello'])

But I cannot explain that because the code above does not anything specific, it simply passes execution through.