A recovery routine defined by the FESTAE macro gets control in the same sequence and under the same conditions as a recovery routine defined by the ESTAE or ESTAEX macro. However, only a type 2, 3, or 4 SVC routine (one for which the system creates an SVRB) can issue FESTAE.
When the SVC routine issues FESTAE, it defines an ESTAE-type recovery routine with minimal processor overhead. The SVC routine can use FESTAE only once to create a recovery routine. Therefore, any SVC routine needing to change its recovery routine address must use branch entry ESTAE services, and any SVC routine needing more than a single recovery routine must use an ESTAEX or ESTAE macro to get the additional recovery routines.
In addition to the parameter area that you can supply by coding the PARAM parameter on the FESTAE macro, a 24-byte parameter area is also available as an option. The name of the optional parameter area is RBFEPARM, which is a field in the RB data area. If you do not specify the PARAM parameter on the FESTAE macro, the system uses RBFEPARM as the default parameter area. When the recovery routine gets control, SDWAPARM (or GPR 2 if the system does not provide an SDWA) contains the address of RBFEPARM. The mainline routine can clear (set to zero) and initialize the parameter area with appropriate information (such as tracking data) that might be useful to the recovery routine. You must clear the parameter area before using it to ensure that no spurious data remains in it from previous processing.