Modify Exception Description (MODEXCPD)


Op Code (Hex) Operand 1 Operand 2 Operand 3
03EF Exception description Modifying attributes Modification option

Operand 1: Exception description.

Operand 2: Space pointer or character(2) constant.

Operand 3: Character(1) scalar.

Description

The exception description attributes specified by operand 3 are modified with the values of operand 2.

Operand 1 references the exception description.

Operand 2 specifies the new attribute values. Operand 2 may be either a character constant or a space pointer to the modification template. When operand 3 is a constant, operand 2 is a character constant; when operand 3 is not a constant, operand 2 is a space pointer.

The value of operand 3 specifies the modification option. If the modification option is hex 01 and operand 2 specifies a space pointer, the format of the modifying attributes pointed to by operand 2 is as follows:

Offset
Dec Hex
Field Name
Data Type and Length
0 0
Template size
Char(8)
0 0
Number of bytes provided for materialization
Bin(4)



(must be at least 10)


4 4
Number of bytes available for materialization
Bin(4) +
8 8
Control flags
Char(2)
8 8
Exception handling action
Bits 0-2



000 = Do not handle. (Ignore occurrence of exception and continue processing.)
001 = Do not handle. (Disable this exception description and continue to search this invocation for another exception description to handle the exception.)
010 = Do not handle. (Continue to search for an exception description by resignaling the exception to the preceding invocation.)
100 = Defer handling. (Save exception data for later exception handling.)
101 = Pass control to the specified exception handler.



8 8
No data
Bit 3



0 = Exception data is returned
1 = Exception data is not returned



8 8
Reserved (binary 0)
Bits 4-15
10 A
--- End ---

If the exception description was in the deferred state prior to the modification, the deferred signal, if present, is lost.

When the no data field is set to exception data is not returned, no data is returned for the Retrieve Exception Data (RETEXCPD) or Test Exception (TESTEXCP) instructions, and the number of bytes available for materialization field is set to 0. This option can also be selected in the object definition table entry of the exception description.

If the modification option of operand 3 is a constant value of hex 01, then operand 2 may specify a character constant. The operand 2 constant has the same format as the control flags entry previously described.

If the modification option is hex 02, then operand 2 must specify a space pointer. The format of the modification is as follows:

Offset
Dec Hex
Field Name
Data Type and Length
0 0
Template size
Char(8)
0 0
Number of bytes provided
Bin(4)



(must be at least 10 plus the length of the compare value in the exception description)


4 4
Number of bytes available for materialization
Bin(4) +
8 8
Compare value length
Bin(2) +



(maximum of 32 bytes)


10 A
Compare value
Char(32)
42 2A
--- End ---

Note: Fields shown here with a plus sign (+) are ignored by the instruction.
The number of bytes in the compare value is dictated by the compare value length specified in the exception description as originally specified in the object definition table.

An external exception handling program can be modified by resolving addressability to a new program into the system pointer designated for the exception description.

The presence of user data is not a modifiable attribute of exception descriptions. If the exception description has user data, it can be modified by changing the value of the data object specified in the exception description.

Authorization Required

Lock Enforcement

Exceptions

06 Addressing

08 Argument/Parameter

10 Damage Encountered

1C Machine-Dependent

20 Machine Support

22 Object Access

24 Pointer Specification

2E Resource Control Limit

32 Scalar Specification

36 Space Management

38 Template Specification

44 Protection Violation