The DEQ macro releases control of one or more serially reusable
resources from the active task. A task ends abnormally if it either
requests an unconditional release of a resource it does not control,
or issues a request that contains incorrect parameters.
When you use DEQ to release control of a resource obtained through
the ENQ macro, certain parameters on DEQ must match the parameters
on the ENQ that assigned control to that resource. Similarly, when
you use DEQ to release control of a resource obtained through the
RESERVE macro, certain parameters on DEQ must match the parameters
on the RESERVE that assigned control to that resource. In the cases
where the parameters must match, the parameter descriptions note that
fact.
An explanation of how to use the DEQ macro
to serialize access to resources appears in z/OS MVS Programming: Assembler Services Guide.
Environment
The requirements for callers of DEQ are:
| Environmental factor |
Requirement |
|---|
| |
|
| Minimum authorization: |
Problem state with any PSW key. |
| Dispatchable unit mode: |
Task |
| Cross memory mode: |
For LINKAGE=SVC: PASN=HASN=SASN
For LINKAGE=SYSTEM: Any
PASN, Any HASN, Any SASN
For LINKAGE=SYSTEM with RMC=STEP:
PASN=HASN, Any SASN
|
| AMODE: |
24- or 31- or 64-bit |
| ASC mode: |
Primary |
| Interrupt status: |
Enabled for I/O and external interrupts |
| Locks: |
No locks held |
| Control parameters: |
Control parameters must be in the primary address
space. |
Restrictions
The caller cannot have an EUT FRR established.
Input register information
Before issuing the DEQ 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
When control returns to the caller, the general purpose registers
(GPRs) contain: - Register
- Contents
- 0-1
- Used as work registers by the system
- 2-13
- Unchanged
- 14
- Used as a work register by the system
- 15
- One of the following:
- If you specify RET=HAVE, if all return codes for the resources
named in the DEQ macro are 0, register 15 contains 0. If any of the
return codes are not 0, register 15 contains the address of a storage
area containing the return codes.
- Otherwise: Used as a work register by the system.
When control returns to the caller, the access registers (ARs)
contain: - Register
- Contents
- 0-1
- Used as work registers by the system
- 2-13
- Unchanged
- 14-15
- Used as work registers by the system
Some callers depend on register contents remaining the same before
and after issuing a service. If the system changes the contents of
registers on which the caller depends, the caller must save them before
issuing the service, and restore them after the system returns control.
Syntax
The standard form of the DEQ macro is written as follows:
| Syntax |
Description |
|---|
| |
|
| name |
name: symbol. Begin name in
column 1. |
| |
|
| ␢ |
One or more blanks must precede DEQ. |
| |
|
| DEQ |
|
| |
|
| ␢ |
One or more blanks must follow DEQ. |
| |
|
| ( |
|
| |
|
| qname addr |
qname addr: A-type address,
or register (2) - (12). |
| |
|
| , |
|
| ,rname addr |
rname addr: A-type address,
or register (2) - (12). |
| |
|
| , |
rname length: symbol, decimal
digit, or register (2) - (12). |
| ,rname length |
Note: rname length must
be coded if a register is specified for rname addr. |
| |
|
| , |
Default: STEP |
| ,STEP |
|
| ,SYSTEM |
|
| ,SYSTEMS |
|
| |
|
| ) |
|
| ,RET=NONE |
Default: RET=NONE |
| ,RET=HAVE |
|
| |
|
| ,UCB=ucb addr |
ucb addr: A-type address, or
register (2) - (12). |
| |
Note: Specify UCB only with SYSTEMS. |
| |
|
| ,LOC=BELOW |
DEFAULT: LOC=BELOW |
| ,LOC=ANY |
|
| |
|
| ,RNL=YES |
Default: RNL=YES |
| ,RNL=NO |
|
| |
|
| ,RELATED=value |
value: any valid macro keyword
specification. |
| |
|
| ,LINKAGE=SVC |
DEFAULT: LINKAGE=SVC |
| ,LINKAGE=SYSTEM |
|
| |
|
Parameters
The parameters are explained as follows.
- (
- Specifies the beginning of the resource description.
- qname addr
- Specifies the address of an 8-character name. The name can contain
any valid hexadecimal characters. The qname must
be the same name specified for the resource in an ENQ or RESERVE macro.
Authorized programs should use a restricted qname (as described under
Minimum authorization in the Environment topic of this chapter) to
prevent interference from unauthorized programs.
- ,
- ,rname addr
- Specifies the address of the name used together with qname and
scope to represent the resource acquired by a previous ENQ or RESERVE
macro. The name must be from 1 to 255 bytes long, can be qualified,
and can contain any valid hexadecimal characters. The rname must be
the same name specified for the resource in an ENQ or RESERVE macro.
- ,
- ,rname length
- Specifies the length of the rname. The length
must have the same value as specified in the previous ENQ or RESERVE
macro. If you omit this parameter, the system uses the assembled
length of the rname. You can specify a value between
1 and 255 to override the assembled length, or you may specify a value
of 0. If you specify 0, the length of the rname must
be contained in the first byte at the rname addr.
- ,
- ,STEP
- ,SYSTEM
- ,SYSTEMS
- Specifies the scope of the resource. If you used the ENQ macro
to obtain control of the resource, the scope you specify on DEQ must
match the scope specified on that ENQ. If you used the RESERVE macro
to obtain control of the resource, you must specify SYSTEMS as the
scope on DEQ.
- )
- Specifies the end of the resource description.
Notes on specifying multiple resources on one DEQ request: - Within a single set of parentheses, you can repeat the qname
addr, rname addr, type of control, rname
length, and the scope until there is a maximum of 255 characters,
including the parentheses.
- The following parameters apply to all the
resources you specify on the request: RET and RNL.
- ,RET=NONE
- ,RET=HAVE
- HAVE specifies that the request for releasing the resources named
in DEQ is to be honored only if the active task has been assigned
control of the resources. A return code is set if the resource is
not held. NONE specifies an unconditional request to release all the
resources. RET=NONE is the default. The active task ends abnormally
if it has not been assigned control of the resources.
- ,UCB=ucb addr
- Specifies the address of a fullword that contains the address
of a UCB for a reserved device that is now being released. This parameter
is used to release a device reserved with the RESERVE macro and is
valid only with a scope of SYSTEMS. The UCB parameter is optional.
Note: The
UCB keyword might contain a UCB address for a UCB that resides in
storage above or below 16 megabytes. If the UCB address might point
to a UCB above 16 megabytes, you must also specify LOC=ANY.
- ,LOC=BELOW
- ,LOC=ANY
- Specifies the location of the input UCB address. ANY specifies
that the input UCB address is to be treated as a 31-bit address. BELOW
specifies that the input UCB address is to be treated as a 24-bit
address. The default is LOC=BELOW.
- ,RNL=YES
- ,RNL=NO
- Specifies whether the system is to perform RNL processing, which
might change the scope value of a resource. You must specify the same
RNL option as you used in the ENQ macro that requested the resource.
The default is RNL=YES.
- ,RELATED=value
- Specifies information used to self-document macros by “relating”
functions or services to corresponding functions or services. The
format and contents of the information specified are at the discretion
of the user, and can be any valid coding values.
- ,LINKAGE=SVC
- ,LINKAGE=SYSTEM
- Specifies the type of linkage the caller is using to invoke the
DEQ service.
For LINKAGE=SVC, the linkage is through an SVC instruction.
This linkage is valid only when the caller is in primary mode and
the primary, home, and secondary address spaces are the same.
For
LINKAGE=SYSTEM, the linkage uses a non-SVC entry. This linkage is
valid in cross memory mode or in non-cross memory mode. LINKAGE=SYSTEM
is intended to be used by programs in cross memory mode.
The default is LINKAGE=SVC.
ABEND codes
For only unconditional requests, the caller might encounter abend
code X'130' or X'530'. For unconditional and conditional
requests, the caller might encounter one of the following abend codes: - X'230'
- X'330'
- X'430'
- X'730'
- X'830'
- X'930'
See z/OS MVS System Codes for
explanations and responses for these codes.
Return and reason codes
Return codes are provided by the system only if RET=HAVE is designated.
If all of the return codes for the resources named in DEQ are 0,
register 15 contains 0. If any of the return codes are not 0, register
15 contains the address of a virtual storage area containing the return
codes as shown in Figure 1. Figure 1. Return Code Area Used by DEQ
The return codes are placed in the parameter list resulting from
the macro expansion in the same sequence as the resource names in
the DEQ macro.
The return codes for the DEQ macro with the RET=HAVE parameter
are described in Table 1.
Table 1. Return
Codes for the DEQ Macro with the RET=HAVE Parameter| Hexadecimal Return Code |
Meaning and Action |
|---|
| 0 |
Meaning: The system has released the resource. Action:
None.
|
| 4 |
Meaning: The resource has been requested
for the task, but the task has not been assigned control of it. The
task continues waiting. (This return code might result if an exit
routine, which received control because of an interruption, issued
the DEQ macro on behalf of the task.) Action: None.
|
| 8 |
Meaning: Control of the resource has not
been requested by the active task, or the resource has already been
released. Action: None required. However, you might take
some action based on your application.
|
Example 2
Unconditionally release control of the resources in Example 2 of
ENQ. The length of the rname for the first resource
is 3 characters and the length of the rname for
the third resource is 8 characters. Allow the length of the second
resource to default to its assembled length. DEQ (MAJOR4,MINOR4,3,STEP,MAJOR2,MINOR2,,SYSTEM, X
MAJOR3,MINOR3,8,SYSTEMS)
|
z/OS MVS Programming: Assembler Services Reference ABE-HSP
Copyright IBM Corporation 1990, 2014