IBM SC33-1683-02 - Manual (Page 92)

End of parameter list indicator
The high-order bit is set on in the last address set in the parameter list to
indicate that it is the last one in the list. On return from your user exit program,
CICS scans the parameter list for the high-order bit to find the last parameter.
Therefore, if you modify the length of the parameter list, you must also reset
the high-order bit to indicate which is the new last address.
The UEPCLPS exit-specific parameter
The UEPCLPS exit-specific parameter is included in both exit XNQEREQ and exit
XNQEREQC. It is the address of the command-level parameter structure. The
command-level parameter structure contains four addresses, NQ_ADDR0 through
NQ_ADDR3. It is defined in the DSECT NQ_ADDR_LIST, which you should copy
into your exit program by including the statement COPY DFHNQUED.
The command-level parameter list is made up as follows.
Note: The relationship between arguments, keywords, data types, and input/output
types is summarized for the enqueue commands in Table 3 on page 62.
NQ_ADDR0
is the address of a 9-byte area called the EID, which is made up as follows:
NQ_GROUP
NQ_FUNCT
NQ_BITS1
NQ_BITS2
NQ_EIDOPT5
NQ_EIDOPT6
NQ_EIDOPT7
NQ_EIDOPT8
NQ_GROUP
Always X'12', indicating that this is a task control request.
NQ_FUNCT
One byte that defines the type of request:
X'04' ENQ
X'06' DEQ
NQ_BITS1
Existence bits that define which arguments were specified. To obtain
the argument associated with a keyword, you need to use the
appropriate address from the command-level parameter structure.
Before using this address, you must check the associated existence bit.
If the existence bit is set off, the argument was not specified in the
request and the address should not be used.
X'80' Set if the request contains an argument for the RESOURCE
keyword. If set, NQ_ADDR1 is meaningful.
X'40' Set if the request contains an argument for the LENGTH
keyword. If set, NQ_ADDR2 is meaningful.
enqueue EXEC interface program exits
60 CICS TS for OS/390: CICS Customization Guide