This sample code will initialize a PDEVOPENSTRUC and use it to call the function.

#define INCL_SPL
#define INCL_SPLDOSPRINT
#define INCL_BASE
#define INCL_ERRORS

#include <os2.h>
#include <stdio.h>
#include <stdlib.h>

VOID main()
{
  HSPL hspl;
  PDEVOPENSTRUC pdata;        /* Pointer to a DEVOPENSTRUC structure */
  PSZ  pszToken = "*";        /* Spooler info identifier             */

  /* Allocate memory for pdata */
  if ( !DosAllocMem( &pdata,sizeof( DEVOPENSTRUC ),
     (PAG_READ|PAG_WRITE|PAG_COMMIT ) )
  {
    /* Initialize elements of pdata */
    pdata->pszLogAddress      = "LPT1Q1";
    pdata->pszDriverName      = "IBMNULL";
    pdata->pdriv              = NULL;
    pdata->pszDataType        = "PM_Q_STD";
    pdata->pszComment         = NULL;
    pdata->pszQueueProcName   = NULL;
    pdata->pszQueueProcParams = NULL;
    pdata->pszSpoolerParams   = NULL;
    pdata->pszNetworkParams   = NULL;

    hspl = SplQmOpen( pszToken,4L,( PQMOPENDATA )pdata );

    if ( hspl != SPL_ERROR )        /* Good spooler handle */
    {
       printf("SplQmOpen handle is %d\n",hspl);
    }
    else
    {
       printf("SplQmOpen failed.\n");
    }
  }
}