Error Handling

Three types of errors can occur when an intrinsic is executed:

Condition code errors. Such errors are generally recoverable since control returns to the calling program. The operating system maintains condition codes to provide backward compatibility with previous (MPE V/E-based) operating systems.
Status parameter errors. When you include the status parameter in the intrinsic call, it returns status information to the calling routine. For some intrinsics, both the condition code and the special status parameter can return information; other intrinsics use only one of these to return information.
Abort errors. Such errors occur when a calling program passes illegal parameters to an intrinsic or does not have the required capability for the intrinsic. An abort error terminates the process.

Condition Code Errors

Some intrinsics have an associated condition code. A condition code is a temporary value providing information about what happened during execution. The condition code is affected by many intrinsics and should be checked immediately upon return from an intrinsic.

A condition code has three possible values (CCG, CCL, or CCE) and has the general meaning as indicated in Table 2-3 “Condition Code Descriptions” Specific meanings are listed under the individual intrinsic called.

Table 2-3 Condition Code Descriptions

Value	Condition Code	Description
0	CCG (>)	Condition Code Greater Than. A warning or special condition occurred but may not have affected the execution of the request. (For example, the request was executed, but default values were assumed as intrinsic call parameters.)
1	CCL (<)	Condition Code Less Than. The request was not granted, but the error condition may be recoverable.
2	CCE (=)	Condition Code Equal. Generally indicates that the request was granted.

Status Parameter Errors

Some intrinsics use the status parameter to return information on the status of the intrinsic call. This parameter is a native mode (NM) implementation of the condition code feature with extended capabilities. The status parameter is a 32-bit signed integer value passed by reference.




	NOTE: It is good programming practice to specify the `status` parameter and check its value after an intrinsic call. If an error or warning condition is encountered and the `status` parameter was not specified, the intrinsic causes the calling process to abort.

The status parameter is read in two 16-bit fields:

Biots: Value/Meaning
16:16: status.subsys: identifies the subsystem that initiated the error or warning.
0:16: status.info: identifies the type of error or warning. Refer to each intrinsic for possible values.

and represent the possible values returned by the status parameter.

Table 2-4 Status.subsys Parameter Identifiers

Subsystem ID	Subsystem
0	Successful (no errors)
9	CM Loader
098	System Aborts
100	Switch
101	Memory Manager
102	Process Manager
103	Stack Unwind
104	NM Loader
107	Virtual Space Management
108	Table Management
110	Clock/Timer Manager
111	High-Level I/O
113	Low-Level I/O
114	HP-IO Channel Manager
116	HP-IB Adapter Manager
121	CS80 Disk Manager
122	Port (IPC) Facility
123	Dispatcher
127	CIPER Device Manager
128	Terminal I/O Manager for Logging
130	Page Printer Device Manager
133	Measurement Interface
143	File System
145	Secondary Storage Management
151	Transaction Management
153	File System Label Management
154	CM Support Routines
155	Job and Session
158	Break Handling
161	Command Interpreter
165	Debug Low-Level Breakpoint Management
169	CM Debugger
185	File System Storage Management
187	Error Management
188	CM Emulator, Translator, OCT
193	Floating-Point Conversion
195	Hewlett-Packard SORT
196	Hewlett-Packard MERGE
198	Eagle A-MUX Device Manager
200	U-Code Trap Handler
201	Data Communication Buffer Manager
206	System Logging
213	I/O Services
221	Intrinsic Aborts
222	Intrinsic Names

Table 2-5 Status.info Parameter Identifiers

Value	Description
0	Normal
<0	Indicates an error condition
>0	Indicates a warning condition

Abort Errors

Software traps are interrupts generated by software events in which the operating system interrupts the normal flow of a process' execution. Some intrinsics generate a software trap when they detect certain error conditions. Normally, if an intrinsic causes a trap, the system trap handler aborts the user program. However, you can write a procedure to handle abort errors and use it in place of the default system trap handler, which will permit recovery from errors in certain cases. For more information on handling traps, refer to Trap Handling Programmer's Guide.

When a program is aborted in a batch job, the operating system removes the job from the system unless you precede the command that caused the error with a CONTINUE command. If the program is aborted in an interactive session, the system returns control to the parent process.

Error Handling

Technical documentation

» Table of Contents

» Index

Condition Code Errors

Status Parameter Errors

Abort Errors