gtpi1m0tSystem Installation Support Reference

Core Resident Enter/Back Macro

User exit routine UCCCREB is called if the exit point named CREB is active. UCCCREB is invoked at the end of macro processing and just before control is passed to the destination program for:

UCCCREB can be called from an ISO-C environment. Exit point CREB is located in copy segment CCEB of CSECT CCENBK and in copy segment CLHL of CSECT CCCLHR.

Multifunction user exit linkage is assembled into this exit point. This user exit is activated by the ZDBUG command (with the START parameter specified), which calls the UXITC macro with the IUX_VADB function set on.

General Conditions at Entry

The registers at entry to UCCCREB are:

R0-R7
When the user exit is called from a non-ISO-C environment, the contents have been restored from the ECB and contain the values that are to be passed to the E-type program that will receive control. When the user exit is called from an ISO-C environment, the application registers are stored in the data save area (DSA) and have not yet been restored.

R8
Base of E-type program to receive control.

R9
Address of the ECB.

R10
Contains 0 if the user exit is called from an ISO-C environment, otherwise it contains a non-zero value.

R11-R15
See User Exit Routines - Common Entry Conditions.

System Conditions at Entry

System state
Problem (see Programming Considerations at Entry, item 1)

System mask
Unmasked (see Programming Considerations at Entry, item 1)

Protect key
Working storage.

Address Space
EVM.

Programming Considerations at Entry

  1. Usually, the system state, system mask, and protection key are as stated. However, there can be exceptions if system programs issued MONTC to get to supervisor state, changed the system mask, or changed the protection key.
  2. You activate the TPF Assembler Debugger for VisualAge Client or TPF C Debugger for VisualAge Client code from this user exit by calling the UXMAC macro. Program load event detection code (the IUX_VADB UXMAC call) must be the last exit routine to be called in the exit. The debugger will not return to this user exit when it determines that the debugger must receive control. If you do not want the debugger to trace the program that will be entered, set the CE3_NO_DEBUG indicator in byte CE3DBCR (page 3 of the ECB) before the debugger is called. The debugger always sets this indicator off before activating the program.
  3. See User Exit Routines - Common Entry Conditions.
  4. See User Exit Routines - Common Programming Considerations for other considerations.

Programming Considerations on Return

See User Exit Routines - Common Return Conditions.

General Conditions on Return

See User Exit Routines - Common Return Conditions.