gtpi1m29System Installation Support Reference

SVC Macro Decoder

User exit routine UCCSVC is invoked from the SVC Macro Decoder for all SVCs, both direct and indexed, if the exit point named SVC is active. Exit point SVC is in CSECT CCMCDC.

General Conditions at Entry

The registers at entry to UCCSVC are:

R6
Address of the macro entry in the macro decoder table.

R8
Base address of E-type program that issued the SVC macro.

R9
Address of the ECB.

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

System Conditions at Entry

System state
Supervisor

System mask
Masked for I/O Interrupts

Protect key
0

Address state
EVM.

Programming Considerations at Entry

  1. The contents of program registers R0-R7 have been saved in the ECB register save area.
  2. To preserve the integrity of the stack, user processing must not issue an SVC macro because this would cause the stack register to be reinitialized and the current saved data to be lost.
  3. The SVC exit point occurs before the formatting of the entry in the macro trace table.
  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.