The _STRING_BUFFER_HEADER structure is used at the beginning of a counter string header block that is returned when retrieving the names or description strings of performance counters. For more information, see Figure 2 in section 3.1.4.1.2.

 typedef struct _STRING_BUFFER_HEADER {
   DWORD dwSize;
   DWORD dwCounters;
 } PERF_STRING_BUFFER_HEADER,
  *PPERF_STRING_BUFFER_HEADER;

dwSize: The total size, in bytes, of the data that is returned.

dwCounters: The total number of counters in the counterset.