SCHEDXIT — Schedule an exit routine for execution

Description

Note: IBM® recommends that you use the SCHEDIRB macro rather than SCHEDXIT to request asynchronous exits.

The SCHEDXIT macro schedules an asynchronous exit routine for execution under a specific task.

Before using this macro, read the description of using asynchronous exits in the z/OS MVS Programming: Authorized Assembler Services Guide.

Environment

The requirements for the caller are:

Environmental factor Requirement
Minimum authorization: Supervisor state with PSW key 0
Dispatchable unit mode: Task or SRB
Cross memory mode: PASN=HASN or PASN¬=HASN
AMODE: 31-bit
ASC mode: Primary
Interrupt status: Enabled for I/O and external interrupts
Locks: Local lock held
Control parameters: None

Programming requirements

If the IQE resides below 16 megabytes, the IQE address that is passed must be a 31-bit address with the high-order byte of the address set to zero.

The caller must have addressability to the address space on which the exit routine is to be dispatched.

Restrictions

None.

Input register information

Before issuing the SCHEDXIT macro, the caller does not have to place any information into any register unless using it in register notation for a particular parameter or using it as a base register.

Output register information

After the caller issues the macro, the system might use some registers as work registers or might change the contents of some registers. When the system returns control to the caller, the contents of these registers are not the same as they were before the caller issued the macro. Therefore, if the caller depends on these registers containing the same value before and after issuing the macro, the caller must save these registers before issuing the macro and restore them after the system returns control.

When control returns to the caller, the general purpose registers (GPRs) contain:
Register
Contents
0
Used as a work register by the system
1
IQE address
2-13
Unchanged
14-15
Used as work registers by the system

Performance implications

None.

Syntax

The standard form of the SCHEDXIT macro is written as follows:

Syntax Description
   
   name name: Symbol. Begin name in column 1.
   
␢ One or more blanks must precede SCHEDXIT.
   
SCHEDXIT  
   
␢ One or more blanks must follow SCHEDXIT.
   
IQE=iqe-address iqe-address: RX-type address or register (2) - (12).
   

Parameters

The parameter is explained as follows:

IQE=iqe-address
Specifies the address of the interrupt queue element (IQE) that defines the task under which the exit routine will execute.

ABEND codes

00A

See z/OS MVS System Codes for an explanation and programmer responses for this code.

Return and reason codes

None.