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► SURROGCHK
Defaults to YES, meaning that a surrogate security check will be performed in
the EXCI client address space if the flowed user ID is different from the user
ID of the client address space. This occurs regardless of the CICS security
settings. This means that if you flow a user ID in an EXCI request (including
flowing a user ID with an External Call Interface [ECI] request using the CICS
TG for z/OS), you will need to either add a RACF surrogate profile, or disable
surrogate security checks by setting this parameter to NO. For details on how
to add surrogate profiles, refer to “SURROGAT security profiles” on page 109.
Refer to the CICS External Interfaces Guide, SC33-1944, for a detailed
description of the DFHXCOPT parameters.
4.2.4 EXCI user-replaceable module: DFHXCURM
The user-replaceable module DFHXCURM is invoked on every EXCI
Allocate_Pipe request, and also after detection of any EXCI retryable errors. This
will occur under one of three circumstances:
► The target CICS region is not available.
► There are no pipes available on the target CICS region.
► IRC has not been active since the last initial program load (IPL).
DFHXCURM can be used to remove the affinity of an EXCI request to a given
CICS region by dynamically modifying the APPLID in the EXCI request. It can
also be used to provide limited workload balancing of EXCI requests across
multiple CICS regions from the CICS TG for z/OS. For further details on this
subject, refer to Workload Management for Web Access to CICS, SG24-6118.
4.2.5 Transactional EXCI
Transactional EXCI works together with MVS resource recovery services (RRS),
and allows multiple EXCI calls to become part of one logical unit of work. This
now means that the CICS TG for z/OS can be used by other transactional
systems (such as WebSphere V4.0 for z/OS) to make transaction requests to
CICS, which can be coordinated using a two-phase commit mechanism between
the two systems.
Restriction: EXCI requests can only be transactional if the address space
using the EXCI and the CICS region execute in the same z/OS image. This is
a restriction imposed by the RRS support in CICS.
To implement transactional EXCI, you must specify the following parameters:
► RRMS=YES in CICS SIT parameter
Chapter 4. EXCI connections to CICS 73