These operations are available in both the traditional syntax
and free-form syntax.
The IN and OUT operations allow you to retrieve and write one or all data
areas in a program, depending on the factor 2 entry.
The IN and OUT operations also allow you to control the locking or unlocking
of a data area. When a data area is locked, it can be read but not updated
by other programs or procedures.
The following lock states are used:
For an IN operation with *LOCK specified, an exclusive allow read lock
state is placed on the data area.
For an OUT operation with *LOCK the data area remains locked after the
write operation
For an OUT operation with blank the data area is unlocked after it is
updated
UNLOCK is used to unlock data areas and release record locks, the data
areas and/or records are not updated.
During the actual transfer of data into or out of a data area, there is
a system-internal lock on the data area. If several users are contending for
the same data area, a user may get an error message indicating that the data
area is not available.
Remember the following when using the IN, OUT, and UNLOCK operations:
A data-area operation cannot be done on a data area that is not defined
to the operating system.
Before the IN, OUT, and UNLOCK operations can be done on a data area,
you must specify the DTAARA keyword on the definition specification for the
data area, or specify the data area in the result field of an *DTAARA DEFINE
statement. (For further information on the DEFINE statement, see DEFINE (Field Definition).)
A locked data area cannot be updated or locked by another RPG program;
however, the data area can be retrieved by an IN operation with factor 1 blank.
A data-area name cannot be the name of a multiple-occurrence data structure,
an input record field, an array, an array element, or a table.
A data area cannot be the subfield of a multiple occurrence data structure,
a data-area data structure, a program-status data structure, a file-information
data structure (INFDS), or a data structure that appears on an *DTAARA DEFINE
statement.
If the name of the data area is determined at runtime, due
to the DTAARA(*VAR) keyword being used, the variable containing the name must
be set before an IN operation. If a data area is locked because of a prior
*LOCK IN operation, any other operations (IN, OUT, UNLOCK) for the data area
will use the previously locked data area, and the variable containing the
name will not be consulted.
If the library name is not specified by the DTAARA keyword,
the library list will be used to locate the data area.
A data structure defined with a U in position 23 of
the definition specifications indicates that the data structure is a data
area. You may specify the DTAARA keyword for a data area data structure, if
specified you can use the IN, OUT and UNLOCK operation codes to specify further
operations for the data area. The data area is automatically read and locked
at program initialization time, and the contents of the data structure are
written to the data area when the program ends with LR on. If the data area
for a data area data structure is not found, it will be created with an initial
value of blanks. If the library list was searched for the data area, the new
data area will be created in QTEMP.
To define the local data area (*LDA) you can do one of the following:
Specify the DTAARA(*LDA) keyword on the definition specification for the
data area.
Specify UDS on the definition specification for the data area and leave
the name blank.
Specify *LDA in factor 2 of a *DTAARA DEFINE statement.
To define the *PDA you may specify the DTAARA(*PDA) keyword on the definition
specification for the data area, or specify *PDA in factor 2 of a *DTAARA
DEFINE statement.