WinCreateMsgQueue

After calling WinInitialize, you must call this function if your thread needs to respond to messages. Save the handle, as other functions need it as input.

Syntax

WinCreateMsgQueue( hab,  lQueuesize )

Parameters

hab (HAB) - input

Anchor block of calling thread (from WinInitialize or WinQueryAnchorBlock).

lQueuesize (LONG) - input

Maximum queue size.

This parameter is ignored for versions higher than version 3 of the OS/2 operating system. The lQueuesize parameter is dynamically allocated. The maximum queue size should be set to zero.

For version 3 and lower of the OS/2 operating system, this parameter is the maximum number of messages that can be queued.

Use the system default queue size which is 10 messages.

Other

Maximum queue size.

Returns

hmq (HMQ) - return

Handle to the newly created message queue. NULLHANDLE is returned if there was an error. WinGetLastError will return one of:

0x100A PMERR_RESOURCE_NOT_FOUND :The specified resource identity could not be found.

0x1011 PMERR_HEAP_OUT_OF_MEMORY :An attempt to increase the size of the heap failed.

0x1012 PMERR_HEAP_MAX_SIZE_REACHED :The heap has reached its maximum size (64KB), and cannot be increased.

0x1018 PMERR_QUEUE_TOO_LARGE :An attempt to create a message queue has failed because the value specified for the size of the message queue is too large.

0x1051 PMERR_NOT_IN_A_PM_SESSION :An attempt was made to access function that is only available from PM programs from a non-PM session.

0x1052 PMERR_MSG_QUEUE_ALREADY_EXISTS :An attempt to create a message queue for a thread failed because a message queue already exists for the calling thread.

Remarks

Most PM calls require a message queue. WinCreateMsgQueue must be issued after the WinInitialize function, but before any other PM calls are invoked. It must be issued only once per thread.

Define (C/C++)

#define INCL_WINMESSAGEMGR
#include <os2.h>

Example Code

#define INCL_WINMESSAGEMGR
#include <os2.h>

HAB hab;
ULONG flOptions = 0L;
HMQ hmq;

hab=WinInitialize(flOptions);
hmq=WinCreateMsgQueue(hab, 0L);

if (hmq) {
          :
         }

Related Functions

• WinBroadcastMsg
• WinCancelShutdown
• WinDestroyMsgQueue
• WinDispatchMsg
• WinGetDlgMsg
• WinGetMsg
• WinInitialize
• WinInSendMsg
• WinPeekMsg
• WinPostMsg
• WinPostQueueMsg
• WinQueryMsgPos
• WinQueryMsgTime
• WinQueryQueueInfo
• WinQueryQueueStatus
• WinSendDlgItemMsg
• WinSendMsg
• WinSetClassMsgInterest
• WinSetMsgInterest
• WinSetMsgMode
• WinSetSynchroMode
• WinTerminate
• WinWaitMsg