APAR PK10591 describes an overlay which occurs when a user (or job, or
started task) attempts to use TCP/IP's RESOLVER service without an OMVS
segment - either an explicit one, or a system-wide default OMVS segment.
If this unfortunate circumstance occurs, RESOLVER can overlay field
UCBNXUCB. According to the APAR text, FDRPAS uses UCBNXUCB.
Actually, almost all FDR components use an internal UCB scan which is
affected by the UCBNXUCB overlay. Innovation sent a notice of this
problem to all our customers, including a circumvention zap to FDR to
avoid the problem even if the overlay has occured.
As Brian said, this is actually a TCP/IP bug that exists only in z/OS
1.6 and 1.7. It occurs when some application calls the TCP Resolver
service, which tries to start a USS (Unix) task. If the task fails to
start, the overlay can occur to some random UCB (it happens to overlay
the last UCB that presented an I/O interrupt on that CPU, so it could be
anything).
The known cause of the failure to start the USS task is when the calling
application does not have a OMVS segment in RACF (or equivalent) and no
system-wide default OMVS segment has been defined. Since an application
should not be calling RESOLVER without a OMVS segment, this is an
application error or an installation error.
In the cases I am aware of, a product from a well-known, large ISV was
involved. Apparently it calls RESOLVER but its installation
instructions do not specify that a OMVS segment is required.
--
Bruce A. Black
Senior Software Developer for FDR
Innovation Data Processing 973-890-7300
personal: [EMAIL PROTECTED]
sales info: [EMAIL PROTECTED]
tech support: [EMAIL PROTECTED]
web: www.innovationdp.fdr.com
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