Return code specifications

On return to component trace, the display routine must place information in the registers. Component trace takes action based on the return codes set by the routine.

Registers on return: On return to component trace, the display routine must place the following information in the registers:

Register	Contents
GPR 0	No requirement.
GPR 1	No requirement.
GPRs 2 - 14	You must restore the contents of these registers.
GPR 15	Return code. On return from a request to provide information, IBM® recommends you set the return codes as follows: 0 The display routine completed successfully; the routine updated the CTSS with the trace display information. Other An error occurred.
ARs 0 - 15	You must restore the contents of these registers.

Component trace processing after return: If the display routine sets a non-zero return code, or it does not set either the CTSSDON, CTSSDOFF or CTSSDMIN bits, the system displays the previous trace information and the trace information returned by the display trace exit routine in CTSS is ignored.