Open feedback area

 

The open feedback area is the part of the open data path (ODP) that contains general information about the file after the program opens the file. It also contains file-specific information, depending on the file type.

The open feedback area contains information about each device or communications session defined for the file. The program sets this information during open processing and the program can update the information as it performs other operations.

The following table provides more detailed information about open feedback areas.

Table 1. Open Feedback Area
Offset Data type Length Contents File type
0 Character 2 Open data path (ODP) type:

DS

Display, tape, ICF, save, printer or diskette file that is not being spooled.

DB

Database member.

SP

Printer or diskette file being spooled or inline data file.
Tape and diskette
2 Character 10 Name of the file being opened. If the ODP type is DS, this is the name of the device file or save file. If the ODP type is SP, this is the name of the device file or the inline data file. Tape and diskette
12 Character 10 Name of the library containing the file. For an inline data file, the value is *N. Tape and diskette
22 Character 10 Name of the spooled file. The name of a database file containing the spooled input or output records. Diskette being spooled
32 Character 10 Name of the library in which the spooled file is located. Diskette being spooled
42 Binary 2 Spooled file number. Diskette being spooled
44 Binary 2 Maximum record length. Tape and diskette
46 Character 2 Reserved.  
48 Character 10 Member name.

If ODP type SP, the member name in the file named at offset 22.

Diskette
58 Binary 4 Reserved.  
62 Binary 4 Reserved.  
66 Binary 2 File type:

1

Display

2

Printer

4

Diskette

5

Tape

9

Save

10

DDM

11

ICF

20

Inline data

21

Database
Tape and diskette
68 Character 3 Reserved.  
71 Binary 2 Not applicable to tape and diskette.  
73 Binary 2 Not applicable to tape and diskette.  
75 Binary 4 Not applicable to tape and diskette.  
79 Character 2 Not applicable to tape and diskette.  
81 Character 1 Not applicable to tape and diskette.  
82 Character 1 Source file indication.

Y

File is a source file.

N

File is not a source file.
Tape and diskette
83 Character 10 Reserved.  
93 Character 10 Reserved.  
103 Binary 2 Offset to volume label fields of open feedback area. Tape and diskette
105 Binary 2 Maximum number of records that can be read or written in a block when using blocked record I/O. Tape and diskette
107 Binary 2 Not applicable to tape and diskette.  
109 Binary 2 Blocked record I/O record increment. Number of bytes that must be added to the start of each record in a block to address the next record in the block. Tape and diskette
111 Binary 4 Reserved.  
115 Character 1 Miscellaneous flags.  
     

Bit 1:

Reserved.
 
     

Bit 2:

File shareable

0

File was not opened shareable.

1

File was opened shareable (SHARE(*YES)).
Tape and diskette
     

Bit 3:

Not applicable to tape and diskette.
 
     

Bit 4:

Not applicable to tape and diskette.
 
     

Bit 5:

Not applicable to tape and diskette.
 
     

Bit 6:

Field-level descriptions

This is always 0 for tape and diskette.

Tape and diskette
     

Bit 7:

DBCS-capable file

0

File is not DBCS-capable.

1

File is DBCS-capable.
Tape and diskette
     

Bit 8:

Not applicable to tape and diskette.
 
116 Character 10 Not applicable to tape and diskette.  
126 Binary 2 File open count. If the file has not been opened shareable, this field contains a 1. If the file has been opened shareable, this field contains the number of programs currently attached to this file. Tape and diskette
128 Binary 2 Reserved.  
130 Binary 2 Not applicable to tape and diskette.  
132 Character 1 Miscellaneous flags.  
     

Bit 1:

Not applicable to tape and diskette
 
     

Bit 2:

Not applicable to tape and diskette.
 
     

Bit 3:

Not applicable to tape and diskette.
 
     

Bit 4:

Not applicable to tape and diskette.
 
     

Bit 5:

Not applicable to tape and diskette.
 
     

Bit 6:

User buffers

0

System creates I/O buffers for the program.

1

User program supplies I/O buffers.
Tape and diskette
     

Bits 7:

Reserved.
 
     

Bits 8:

Not applicable to tape and diskette.
 
133 Character 2 Open identifier. The value is unique for a full open of a file (SHARE(*NO)) or the first open of a file with (SHARE(*YES)). This is used for display and ICF files, but is set up for all file types. It allows you to match this file to an entry on the associated data queue. Tape and diskette
135 Binary 2 Maximum record format length, including both data and file-specific information such as first-character forms control, option indicators, response indicators, source sequence numbers, and program-to-system data. If the value is zero, then use the field at offset 44. Tape and diskette
137 Character 2 Not applicable to tape and diskette.  
139 Character 1 Not applicable to tape and diskette.  
140 Character 6 Reserved.  
146 Binary 2 Number of devices defined for this ODP. For displays, this is determined by the number of devices defined on the DEV parameter of the Create Display File (CRTDSPF) command. For ICF, this is determined by the number of program devices defined or acquired with the Add ICF Device Entry (ADDICFDEVE) or the Override ICF Device Entry (OVRICFDEVE) command. For all other files, it has the value of 1. Tape and diskette
148 Character   Device name definition list. See Device definition list for a description of this array. Tape and diskette

 

Parent topic:

Feedback area layouts