The application program and run-time environment are responsible for managing the contents of the Floating Point Control (FPC) register. The system will normally not change the FPC register settings of an existing MVS™ task or SRB.
The S/390® linkage convention for the Floating Point Registers and the FPC register in described in Linkage conventions. To summarize the convention, FPRs 0 to 7 are volatile and FPRs 8 to 15 are non-volatile across a call. The FPC register is non-volatile except for two fields: the IEEE exception flags and the DXC, which are volatile.