gtpi1m0rSystem Installation Support Reference

CCCTIN (CT99)

The CTIN user exits are invoked in copy segment CT00 of CSECT CCCTIN. They are nondynamic exit points that do not follow the standards set by the other exit points. The exit routines are not in CUSR. Instead, they have their own copy segments, CT25, CT26, and CT99 in CCCTIN. The user exits control list (UCL) is not used, nor are the linkage macros used. This is because during initialization, many control program tables and system stacks are not yet available.

The CCCTIN exit permits the user to reserve and initialize main storage for user definition.

To activate exit points CT25 and CT99, you must change the statement at the beginning of each copy segment from EQU INIT00 to DS F.

CT00 tests for the relative location of CT25 and CT99. If the result is 0, the exit points are bypassed. CT26 is activated only when CT25 is in use. Refer to the commentary in the program listing for copy members CT25, CT26, and CT99 for additional information.

General Conditions at Entry

The registers at entry to CT99 are:

R8
Base of CTIN

R9
Base of CT99

R14
Return address.

System Conditions at Entry

System state
Supervisor

System mask
Masked

Protect key
0

Address space
SVM.

Programming Considerations at Entry

CT99 is provided to allow users to initialize/key protect user unique main storage tables, allocated by CT25 and CT26, or other user-unique structures, such as user CINFC labels.

Programming Considerations on Return

R8
Must still contain the base of CTIN.

General Conditions on Return

The System Mask, System State, and Protect Key must be the same as on entry to CT99.