IBM SC33-1683-02 - Manual (Page 218)

System termination program exit XSTERM
The XSTERM exit could be used to output final statistics to your statistics SMF data
sets, and to close them. (Note that CICS VSAM and BDAM data sets have already
been closed by CICS file control before the exit is invoked.)
Exit XSTERM
When invoked
During the second quiesce stage of a normal system shutdown,
immediately before the transient data and temporary storage buffers are
cleared. The exit is not invoked during an IMMEDIATE shutdown.
Exit-specific parameters
None.
Return codes
UERCNORM
Continue processing.
XPI calls
All XPI calls except WRITE_JOURNAL_DATA can be used. However, their
use is not recommended, because they could cause the task to lose
control, thus allowing another task to write more monitoring data.
system termination program exit
186 CICS TS for OS/390: CICS Customization Guide