IBM SC33-1683-02 - Manual (Page 752)

General notes
The following comments apply to the chapters in Part 7 of this book:
v The only aspects of CICS security processing covered are:
– Invoking a user-written external security manager
– Writing a “good night” transaction.
For a comprehensive view of security processing using the Resource
Access Control Facility (RACF) product, see the
CICS RACF Security
Guide.
v Upon return from any customer-written program, CICS must always receive
control in primary-space translation mode, with the original contents of all
access registers restored, and with all general-purpose registers restored
(except for those which provide return codes or linkage information).
For information about translation modes, refer to the IBM ESA/370
Principles of Operation manual.
720 CICS TS for OS/390: CICS Customization Guide