IBM Enhanced 32-Bit Interface Presentation Space IDs

For IBM® Enhanced EHLLAPI applications, the session ID is extended with three additional bytes. These extended session bytes must be set to zero for future compatibility. This is most easily accomplished by setting the contents of EHLLAPI buffers to all binary zero before filling them in with the required information. For example, the following might be used to query the status of session B:
  #include "hapi_c.h"
  int HFunc, HLen, HRc;                                 // Function parameters
  struct HLDPMWindowStatus StatusData;                  // Function parameters
  HLen = sizeof(StatusData);
  HRc  = 0;
  // Set data buffer to zeros and fill in request
  memset(&StatusData, 0x00, sizeof(StatusData));
  StatusData.cwin_shortname = 'B';     // Short session ID
  StatusData.cwin_option    = 0x02;    // Query command
  hllapi(&Func, (char *)&StatusData, &HLen, &HRc);