The register contents on return from a recovery routine depend
on whether the system provided an SDWA. ESTAE-type recovery routines
that receive an SDWA can use any register without saving its contents,
except GPR 14. The routines must maintain the return address supplied
in GPR 14. The routines do not have to place any information in the
registers for use by the system.
ESTAE-type recovery routines that
do not receive
an SDWA must set one of the following return codes in GPR 15:
- Return Code
- Meaning
- 0
- The recovery routine requests percolation.
- 4
- The recovery routine requests a retry. The
recovery routine must then place the address of the retry routine
in GPR 0.
- 16 (X'10')
- Valid only for an ESTAI recovery routine. The system should
not give control to any further ESTAI routines, and should abnormally
end the task.