IBM SC33-1683-02 - Manual (Page 183)

UERCBYP
CICS does not attempt to define the log stream. The process that
was attempting to use the log stream may fail (for example, a data
set open).
XPI calls
All can be used.
API and SPI commands
Must not be used.
An example of how XLGSTRM can be used
Imagine that you have 200 CICS regions, running on, say, 20 MVS images. To
avoid having to define explicitly each log stream used by each CICS region, you
decide to use model definitions. Log streams will be defined to MVS dynamically on
their first usage, with an XLGSTRM exit program being used to select from
alternative model log streams. This is how it might work:
1. On an intitial start of a CICS region, the INITPARM system intialization
parameter specifies:
INITPARM=(Exit_enabler_pgmname=nnn)
where:
v Exit_enabler_pgmname is the name of the program that enables the
XLGSTRM user exit program.
v nnn is a number that identifies the CICS region.
2. The program that enables the XLGSTRM user exit program issues an EXEC
CICS ASSIGN INITPARM command to retrieve the value nnn , and places it in
the exit program’s global work area.
3. When the region tries to connect to its system log, because the log stream is
not defined the XLGSTRM exit program is invoked. The exit program selects
model CICS.DFHLOG.MODELnnn.
log manager domain exit
Chapter 1. Global user exit programs 151