During generalized trace facility (GTF) initialization, GTF received a request to trace start input/output (SIO) events. In MVS/XA, the start subchannel (SSCH) event replaced the SIO event. To maintain compatibility with MVS/370 procedures, GTF accepts the SIO request and treats it as a SSCH trace option request.
GTF initialization continues.
Generalized trace facility (GTF)
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