January 18, 2012
Dear (E)JES customers,
The purpose of this notice is to alert you to a situation that could result in an outage in your environment.
The I/O driver used by (E)JES and the Phoenix TP Monitor, first delivered in 2007 with (E)JES V4R5, acquires its IOBE in private area storage for non-zHPF channel programs. This will lead to abend0C4s in IBM's IOSVSSCH module for systems with IBM APAR OA37420 applied. On those systems, IOSVSSCH attempts to load the new IOBECTKN field (added by the APAR) while running in an SRB dispatched to another address space. The abend0C4 occurs because the IOBE is not in common storage. The outage occurs because an IPL is necessary to back out the IBM APAR.
You will also experience "hangs" in (E)JES and related programs because the abend0C4 in IOSVSSCH occurs at a point before the SSCH is issued to actually initiate the I/O operation in the hardware. The I/O-issuing program, believing the I/O has been asynchronously started by IOS, will WAIT forever expecting an interrupt that never arrives.
For zHPF channel programs, the I/O driver is already acquiring the IOBE in common storage. Therefore, zHPF channel programs are not exposed to this problem.
APAR OA37420 closed on November 16, 2011. The PTFs became generally available on November 30, 2011. Because the APAR is marked HIPER, there is a good chance it will be installed ahead of other service on your system(s).
This issue is addressed by the following (E)JES service:
With this service applied, the I/O driver will acquire the non-zHPF IOBE in common storage, just as is done today for zHPF I/O.
No IPL is required after applying this service. If (E)JES is LPA-resident, the updated programs can be refreshed with a SETPROG LPA,ADD command. Otherwise, a MODIFY LLA,REFRESH command will make the corrected logic available to your TSO/E users. The CEMT SET PROGRAM NEW command can be used in the CICS environment to make the updated code available without recycling CICS. The Phoenix TP Monitor must be recycled after applying the service in order for the fix to take effect in that environment.
We hope this alert reaches you in time to prevent any inconvenience.
Phoenix Software International