Menu program on z/OS

In the TSO environment, the menu program is invoked by the CLIST. In the CICS environment, the program is invoked by transaction MAIL.

The menu program (CSQ4TVD1 for TSO, CSQ4CVD1 for CICS) is the initial program in the suite. It displays the menu (CSQ4VDP1 for TSO, VD1 for CICS) and invokes the other programs when they are selected from the menu.

• In the CICS version of the program, if the user has signed on to CICS, the user ID is obtained by using the CICS command ASSIGN USERID. If the user has not signed on, the program displays the sign on panel (CSQ4VD0) to prompt the user to enter a user ID. There is no security processing within this program; the user can give any user ID.
• In the TSO version, the user's ID is obtained from TSO in the CLIST. It is passed to the menu program as a variable in the ISPF shared pool.

After the program has obtained the user ID, it checks to ensure that the user has a mail queue (CSQ4SAMP.MAILMGR. userid ). If a mail queue does not exist, the program creates one by putting a message on the system-command input queue. The message contains the IBM MQ for z/OS command DEFINE QLOCAL. The object definition that this command uses sets the maximum depth of the queue to 9999 messages.

The program also creates a temporary dynamic queue to handle replies from the system-command input queue. To do this, the program uses the MQOPEN call, specifying the SYSTEM.DEFAULT.MODEL.QUEUE as the template for the dynamic queue. The queue manager creates the temporary dynamic queue with a name that has the prefix CSQ4SAMP; the remainder of the name is generated by the queue manager.

The program then opens the user's mail queue and finds the number of messages on the queue by inquiring about the current depth of the queue. To do this, the program uses the MQINQ call, specifying the MQIA_CURRENT_Q_DEPTH selector.

The program then performs a loop that displays the menu and processes the selection that the user makes. The loop is stopped when the user presses the PF3 key. When a valid selection is made, the appropriate program is started; otherwise an error message is displayed.