Module files 

Files. ASSIGN names a DD, and only the operator maps a DD to a host file, as JCL does, so a program reaches no file it was not given. A binary DD holds z/OS records byte for byte: fixed-length records back to back, or variable-length records each behind a 4-byte RDW. A text DD holds UTF-8 lines, converted through the program’s code page, and placed as a printer would place them (Open::print). Sequential files stream; indexed and relative files are held in memory (see Keyed).

Structs

Dd

Dds

The DDs a run may use: given explicitly, or read from DD_<NAME> in the environment.

Found

A record READ found.

KeySpan

Where a key lies in a record.

Keyed

An indexed or relative file, or a sequential file opened I-O, held in memory from OPEN to CLOSE. The DD holds the records in key (or record-number) order, as an IDCAMS REPRO unload of a KSDS or RRDS does, and CLOSE writes them back that way when they changed.

Open

Enums

FileStatus

An I/O status, as FILE STATUS receives it.

Format

Keying

How the records of a file held in memory are keyed. Record numbers and positions are held as eight big-endian bytes, so that they sort.

Move

A movement of the paper, as a text DD shows it: line feeds, or a form feed.

Record

What a READ found.

Constants

MAX_RELATIVE

The highest relative record number: past it WRITE is a boundary violation (status 24). It stands in for the space a cluster is defined with, so that a stray record number cannot make CLOSE write millions of empty slots.

Functions

absent

An OPTIONAL input file with no DD: every READ is at end.

clear_open_mark

Removes the data set’s open mark, if it has one.

left_open

Whether a run left the VSAM data set at data_set open for output.

number_of

open

open_keyed

Opens a file held in memory. With no DD (an OPTIONAL file) or no file at the DD’s path, it starts empty; OUTPUT always starts empty. record_len is the longest record.

open_mark

The file beside a VSAM data set that marks it open for output, as the catalog’s open-for-output indicator does: an OPEN OUTPUT, I-O or EXTEND makes it and the CLOSE after it removes it, so a data set a run left open keeps it for the next OPEN to verify (numeric::assumptions::VSAM_DATA_SET_LEFT_OPEN).

record_number