Control

The Control service is used by a transaction scheduler to control the operational characteristics of a specified LU. Control allows a transaction scheduler to temporarily halt or resume processing of inbound Allocate requests received for the LU.

When a transaction scheduler requests that processing be halted for an LU, all subsequent inbound Allocate requests received for that LU are rejected with a sense code of X'084C0000' (TP_Not_Available_No_Retry). However, inbound Allocate requests that have already been received and are being processed will not be halted. Thus, the transaction scheduler can receive inbound Allocate request messages for the LU after Control has been issued. In addition, if the scheduler is processing protected conversations, APPC/MVS continues to accept inbound resynchronization requests for the LU, even after the scheduler issues the Control service. For more information about protected conversations, see General Transaction Scheduler Function: From Start-up to Termination.

The LU specified must be assigned to the transaction scheduler requesting the service through the SCHED keyword on the LUADD statement in the APPCPMxx parmlib member.

Environment

Authorization:

Supervisor state or PSW key 0-7

Dispatchable unit mode:

Task 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. ATBCNTL - Control

CALL ATBCNTL (LU_name, 
              Function, 
              Return_code
             );

Parameters

LU_name

Supplied parameter

Type: Character string
Char Set: 01134
Length: 8 bytes

Specifies the name of the LU.

Function

Supplied parameter

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

The Function specifies how the LU operation is to be changed. Valid values for this parameter are:

Value: Meaning
0: Halt_Input
Specifies that APPC/MVS should temporarily halt processing of inbound Allocate requests to the specified LU. The requests are rejected with a sense code of X'084C0000' (TP_Not_Available_No_Retry).
1: Resume_Input
Specifies that APPC/MVS should resume processing of inbound Allocate requests to the specified LU.
2: Halt_All_Input
Specifies that APPC/MVS should temporarily halt processing of Allocate requests to all of the LUs belonging to the transaction scheduler. The requests are rejected with a sense code of X'084C0000' (TP_Not_Available_No_Retry). Only those LUs currently in Active or Outbound_Only state are immediately placed in Outbound_Only state. Those LUs currently in Pending state are eventually placed in Outbound_Only state; the update is not immediate. The state of LUs added by a subsequent SET command will be set to Outbound_Only. (See the LU_Initial_Status parameter of the Identify service for more information.)
3: Resume_All_Input
Specifies that APPC/MVS should resume processing of Allocate requests to all of the LUs belonging to the transaction scheduler. Only those LUs currently in Active or Outbound_Only state are immediately resumed. Those LUs currently in Pending state are eventually placed in Active state; the update is not immediate. The state of LUs added by a subsequent SET command will be set to Active. (See the LU_Initial_Status parameter of the Identify service for more information.)

Return_code

Returned parameter

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

Control might return one of the following decimal values in the return code parameter:

Decimal: Meaning
0: Request accepted.
4: Request accepted. One or more requested LUs were not in the appropriate state for the requested function.
8: The LU_name parameter was not valid or was not assigned to the transaction scheduler making the request.
12: The LU is in a state (pending or in_termination) that cannot be changed by this service.
16: The function value specified was not valid.
32: The requested service is not supported in the caller's environment. For example, this return code will be given if the caller invokes any of the transaction scheduler services while holding a lock.
34: The requested transaction scheduler service must be invoked from a transaction scheduler address space.
44: APPC/MVS is not active.
48: APPC/MVS services failure.

Characteristics and Restrictions

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