Victor Gil wrote:
I need to "compress" 16-byte STCKE format TOD into a 12 byte field without
losing the sysplex-wide uniqueness.
So, I thought I'd keep the first 10 bytes and the last 2 bytes [Programmable
Field].
To my surprise STCKE returns non-zeroes in the bytes #13 and #14 -
????
00C3CD5B F16F38C5 A8000000 01040002
Could someone explain what are these 2 bytes for?
The Principles of Operation is pretty clear about it:
"When the value of a running clock is stored by STORE CLOCK EXTENDED, the value
in bit positions 64-103 of the clock (bit positions 72-111 of the storage
operand) is always nonzero; this ensures that values stored by STORE CLOCK
EXTENDED are always unique when compared with values stored by STORE CLOCK or
STORE CLOCK FAST, extended on the right with zeros."
Also, how save is the assumption that the field can be compressed into 12
byte without losing its sysplex-wide uniqueness.
Given the above, not at all.
Bob
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