SQL's TIMESTAMP_FORMAT causes MCH3601

This problem is different from the one I posted here a few days ago (Data
mapping error on timestamp in SQL insert). Arco correctly diagnosed that
issue with the CHAR function dropping the leading zeros; I fixed the
problem by replacing CHAR with DIGITS. More background: The file being
queried in the query is the outfile from Carsten Flensburg's EXTJRNDTA
utility; that outfile is basically the outfile from DSPJRN with the space
consumed by JOESD redefined for the journaled file's record format. So,
the joDate and joTime fields used in the timestamp_format come from DSPJRN.

I am now sporadically getting MCH3601 (Pointer not set for location
referenced), followed by CPF503E (User-defined function error on member
EJD$CHARGE):
CAUSE: An error occurred while invoking user-defined function
TIMESTAMP_FORMAT in library QSYS2. The error occurred while invoking the
associated external program or service program QQQSVUSR in library QSYS,
program entry point or external name QQQTimestamp_Format, specific name *N.
The error occurred on member EJD$CHARGE file EJD$CHARGE in library
DBALEIQX. The error code is 2. The error codes and their meanings follow:
2 -- The external program failed before it completed.
RECOVERY: For error codes 1 and 2, determine the cause of the error from
either the SQLSTATE or a previously listed message.

Yesterday, when the query (below) ran from a RUNSQL command in batch, it
issued MCH3601 and CPF503E. When I ran the exact same query in interactive
SQL, it ran fine. Today, as I was preparing this post, I ran the same
query in interactive SQL, and got MCH3601 and CPF503E. When I ran it a
second time, it ran fine, and inserted all of the expected records in the
target file. Given that the MCH3601/CPF503E seems to be associated with
the timestamp_format function, would a call to IBM be in order?

Insert into IQX003H
select case
when (JOCODE, JOENTT) = (‘R’, ‘PT’ ) then ‘I’
when (JOCODE, JOENTT) = (‘R’, ‘UB’ ) then ‘B’
when (JOCODE, JOENTT) = (‘R’, ‘UP’ ) then ‘A’
when (JOCODE, JOENTT) = (‘R’, ‘DL’ ) then ‘D’
end,
timestamp_format( joDate || digits(joTime ), ‘MMDDYYHH24MISS’),
next value for IQX003Hseq,
SU_CRGID, SU_PATID, SU_ACCT, SU_OWNID, SU_DR, SU_RDR, SU_PVDID, SU_ORGID,
SU_SUBORG, SU_AGREEID, SU_ID1, SU_ID2, SU_ID3, SU_ORGINID, SU_DOS, SU_CHRG,
SU_PAID, SU_BAL, SU_DIAG, SU_CPT, SU_DESC, SU_DWNPMT, SU_WHOPVD, SU_LOCNAM,
SU_BALSRC, SU_BALTYP, SU_INSID1, SU_INSUPY1, SU_IREJDE1, SU_INSID2,
SU_INSUPY2, SU_IREJDE2, SU_INSID3, SU_INSUPY3, SU_IREJDE3, SU_STATUS,
SU_PIFDAT, SU_PIFTIM, SU_PIFUSR, SU_PIFPGM, SU_DELDAT, SU_DELTIM,
SU_DELUSR, SU_DELPGM, SU_PVDPTD, SU_LSTPDP, SU_LSTSTMD, SU_LSTSTM#,
SU_STMCNT, SU_CODE1, SU_C1RDTE, SU_CODE1DT, SU_CODE2, SU_C2RDTE,
SU_CODE2DT, SU_CODE3, SU_C3RDTE, SU_CODE3DT, SU_CODE4, SU_C4RDTE,
SU_CODE4DT, SU_CODE5, SU_C5RDTE, SU_CODE5DT, SU_HDATE, SU_FEEPLAN,
SU_RREQUST, SU_RREQDTE, SU_RREQWHO, SU_RREQPDT, SU_QCOUNT, SU_QDATE,
SU_QWHO, SU_N1, SU_N2, SU_N3, SU_N4, SU_N5, SU_N6, SU_N7, SU_N8, SU_N9,
SU_N10, SU_A1, SU_A2, SU_A3, SU_A4, SU_A5, SU_A6, SU_A7, SU_A8, SU_A9,
SU_A10, SU_D1, SU_D2, SU_D3, SU_D4, SU_D5, SU_D6, SU_D7, SU_D8, SU_D9,
SU_D10, SU_ENTDAT, SU_ENTTIM, SU_ENTUSR, SU_ENTPGM, SU_UPDDAT, SU_UPDTIM,
SU_UPDUSR, SU_UPDPGM from QTEMP/EJD$CHARGE

- Dan