SYSLOG facility of ISC cache are entries in cyclic buffer so when it is filled up then a new entries overwrite old.
Since it is important information about OS errors or key errors in cache kernel it might be desirable to hold this info during longer time than overwriting starts to happen or cache restarted .

^%z.syslog utility relogs SYSLOG info into a file or global and can be stared as daemon as COS job command for example SYSTEM^%ZSTART or as system task.

SYSTEM^%ZSTART
 J relog^%z.syslog("file:"_$zu(12)_"sys.log",1)

For details see comment before routine label.
It is expected to load it and compile into %SYS namespace.

This function appeared in isc_stat package.