Request_to

Equivalent to:

LU 6.2 (MC_)Request_to_Send
CPI Req_to_Send (CMRTS)

Notifies the partner program that the local program is requesting to enter Send state for the conversation. The conversation will be changed to Send state when the local program subsequently receives a send indication from the partner program.

Requirements

Authorization:

Supervisor state or problem state, any PSW key

Dispatchable unit mode:

Task or SRB mode

Cross memory mode:

Any PASN, any HASN, any SASN

AMODE:

31-bit

ASC mode:

Primary or access register (AR)

Interrupt status:

Enabled for I/O and external interrupts

Locks:

Unlocked

Control parameters:

All parameters must be addressable by the caller and in the primary address space.

Format

Figure 1. ATBRTS - LU 6.2 Request to Send

CALL ATBRTS(
        Conversation_id,
        Notify_type,
        Return_code
       );

Parameters

Conversation_id

Supplied parameter

Type: Character string
Char Set: No restriction
Length: 8 bytes

Conversation_id, sometimes called the resource identifier, identifies a conversation to the system.

Notify_type

Supplied parameter

Type: Structure
Char Set: N/A
Length: 4-8 bytes

Specifies the type of processing and notification (synchronous or asynchronous) requested for this service. Programs can request asynchronous processing, which returns control to the program immediately and later notifies the program by ECB when the service is complete. The possible types are:

None
No notification is requested. The service is performed synchronously, and control is returned to the caller when processing is complete. All returned parameters are set on return to the caller. To specify no notification, set the parameter value to a four-byte structure containing binary zeros.
ECB
Programs can request asynchronous processing by specifying an ECB to be posted when processing completes. To specify an ECB, set the parameter to an eight-byte structure containing a fullword binary one (X'00000001') followed by the address of a fullword area to be used as the ECB. The ECB must reside in the home address space.

When you specify an ECB, control is returned before processing is complete, with only the return code set. If the asynchronous request was accepted, the return code is set to 0 to indicate that the service is being processed asynchronously. Other returned parameters are filled in during asynchronous processing, and the specified ECB is posted when all returned parameters are set. The completion code field in the ECB contains the return code for the service.

Return_code

Returned parameter

Type: Integer
Char Set: N/A
Length: 32 bits

Return_code specifies the return code that is returned to the local program. In cases where an error code is returned, the program should not examine any other returned variable associated with the call as nothing is placed in the variables.

See the following section for descriptions of return codes that can be returned to a caller of Request_To_Send.

Return Codes

Valid return code values for the Return_code parameter are:

Table 1. Return Codes for the Request_to_Send Service
Return Code	Value, Meaning, and Action
0	Value: OK Meaning: The call completed successfully. System Action: If the call specified a Notify_type of ECB, APPC/MVS posts the ECB specified on the Notify_type parameter when APPC/MVS finishes processing the call asynchronously. Application Programmer Response: None required.
20	Value: Product_specific_error Meaning: The system found a product-specific error. System Action: The system might write symptom records, which describe the error, to the logrec data set. Application Programmer Response: See Diagnosing Problems with APPC/MVS TPs for methods to use to diagnose the return code. See Error_Extract for the Error_Extract calling format. If necessary, see Diagnosing Product-Specific Errors for more information about product-specific errors.
24	Value: Program_parameter_check Meaning: The system detected a program parameter check. System Action: The system returns this return code to the caller of the APPC service in error. Application Programmer Response: See Diagnosing Problems with APPC/MVS TPs for methods to use to diagnose the return code. See Error_Extract for the Error_Extract calling format.
25	Value: Program_state_check Meaning: The Sync_level is set to syncpt, and the TP is in the Backout-required state. System Action: The state of the conversation remains unchanged. For a list of states that are valid for each call, see APPC/MVS Conversation State Table. The conversation was in send state and the TP started, but the TP did not finish sending a logical record. Application Programmer Response: See Diagnosing Problems with APPC/MVS TPs for methods to use to diagnose the return code. See Error_Extract for the Error_Extract calling format.

Restrictions

Transaction programs that call the Request_to_Send service while in task mode should not have any enabled unlocked task (EUT) functional recovery routines (FRRs) established. For more information about EUT FRRs, see the section on providing recovery in z/OS MVS Programming: Authorized Assembler Services Guide.