Clocks and time stamps

In CICS PA, the term clock is distinguished from the term time stamp:

Clock
A 32-bit value, expressed in units of 16 microseconds, accumulated during one or more measurement periods. The 32-bit value is followed by 8 reserved bits, which are in turn followed by a 24-bit value indicating the number of measurements periods.

Neither the 32-bit timer component of the clock nor its 24-bit period count are protected against wraparound. The timer capacity is about 18 hours, and the period count runs to modulo-16 777 216.

The eight reserved bits have the following significance:

Bits 0, 1, 2, and 3
Used for online control of the clock when it is running, and should always be zero on output.
Bits 4 and 7
Not used.
Bits 5 and 6
Used to indicate, when set to 1, that the clock has suffered at least one out-of-phase start (bit 5) or stop (bit 6).
Time Stamp
An 8-byte copy of the output of a STCK instruction.