To explain the unit used when defining a value for the XCOM.GLB parm STAT_FREQUENCY
No, STAT_FREQUENCY is not in seconds. STAT_FREQUENCY specifies the number of records (or blocks, if using packing) that are sent/received before the queue files get updated.
A low value causes the queue files to get updated more often. This allows the Queue Status window to get updated frequently but also increases the contention on the queue files.
A high value causes the queue files to get updated less often and the Queue Status window may be a bit behind in displaying the current status of a transfer. However, this also reduces some of the contention on the queue files and can also increase transfer performance, as the overhead of extra updates to the queue files are removed.