How to increase the message queue size in IPC

[Jase21]

How to increase the message queue size in IPC in
the msgsnd() and msgrcv().

//file1.c
#include <stdio.h>
#include <sys/types.h>
#include <sys/msg.h>

struct msgbuf {
	int msgtype;
	char msgtext[21];
}msg;

main()
{
	int mid;
	
	mid = msgget(012, IPC_CREAT);
	if(mid < 0) 
		printf("\nError");
	else {
		msg.msgtype = 1;
		printf("\nEnter the message: ");
		scanf("%s", msg.msgtext);
		msgsnd(mid, msg.msgtext, msg.msgtype, 0);
	}
}

//file2.c
#include <stdio.h>
#include <sys/types.h>
#include <sys/msg.h>

struct msgbuf {
	int msgtype;
	char msgtext[21];
}msg;

main()
{
	int mid;
	
	mid = msgget(012, IPC_CREAT);
	if(mid < 0) 
		printf("\nError");
	else {	
		msgrcv(mid, msg.msgtext, sizeof(msg.msgtext), 0, 0);
		printf("\nRecieved message: %s", msg.msgtext);
	}
	msgctl(mid, IPC_RMID, NULL);
	printf("\n");
}

When i enter hello world
the complete string doesn't be recieved.
Please help.
Please reply at the earliest.
Thank You.