IBM System/360 System Programmer's Guide

To determine if an error is permanent, you should check the "ECB
code" field of the input/output block. To determine the type of error,
check the channel status word and the sense information. If you use the
return address in register 14 to r.eturn control to the system, the
channel program is posted complete, and its request element is made
available. You may use the following optional return addresses:
• Contents of register 14 plus 4 - The channel program is not posted
complete, but its request element is made available.
• Contents of register 14 plus 8 - The channel program is not posted
complete, and its request eleITent is placed back on the request
queue so that the request can be retried. For correct re-execution
of the channel program, you rrust re-initialize the "Flags~" and
"Flags 2" fields of the input/output block and set the "Error
Counts" field to zero.
• Contents of register 14 plus 12 - The channel program is not posted
complete, and its request element is not made available. (The
request element is assumed to be used in a subsequent asynchronous
exit. )
You may
use registers 10 through 13 in an abnormal end appendage
without saving and restoring their contents.
EXCP PROGR8MMING SPECIFICATIONS
This section describes the parameters of the macro-instructions that
you must use with EXCP, and the fields of the required control blocks.
MACRO-INSTRUCTIONS
If you are using the EXCP macro-instruction you must also use DCB,
OPEN, CLOSE, and, in some cases, the EOV macro-instruction. The
parameters of these macro-instructions, and of the EXCP macro-
instruction itself, are listed and explained here. A diagram of the
data control block is included with the description of the DCB
macro-instruction.
DCB -- Define Data Control Block for EXCP
The EXCP form of the DCB macro-instruction produces a data control
block that can be used with the EXCP macro-instruction. You must issue
a DCB macro-instruction for each data set to be processed by your
channel programs. Notation conventions and format illustrations of the
DCB macro-instruction are given in the publication IBM System/360
Operating System: Control Program Services, Form C28-6S41. DCB parame-
ters that apply to EXCP may be divided into four categories, depending
on the following portions of the data control block that are generated
when they are specified:
84
• Foundation block. This portion is required and is always 12 bytes
in length. You must specify the two parameters in this category.
• EXCP interface. This portion is optional. If you specify any
parameter in this category, 20 bytes are generated.
• Foundation block extension and cowmon interface. This portion is
optional and is always 20 bytes in length. If this portion is
generated, the device dependent portion is also generated.
• Device dependent. This portion is optional and is generated only if
the foundation block extension and common interface portion is

IBM System/360 Specifications

General

Brand	IBM
Model	System/360
Category	Desktop
Language	English