Data Manipulation Language Statements › SNAP (DC/UCF)

SNAP (DC/UCF)

The SNAP statement requests a memory snap of one or all of the following areas:

• Task areas—Includes all resources associated with the issuing task, as well as the task control element (TCE) and dispatch control element (DCE) for the task. Information displayed by the snap is formatted with headers.
• System areas—Includes areas for all tasks and internal system control blocks. Task areas are not itemized separately. Information displayed by the snap is formatted with headers.
• Specified locations in memory—Includes one or more areas of memory specifically requested by location and length. The information displayed is not formatted with headers.

The areas requested in the SNAP request are written to the system log file, which is defined during system generation as a sequential dataset or a dictionary area.

Syntax

►►─── SNAP ─┬─────────────────┬───────────────────────────────────────────────►
            └─ TITLE (title) ─┘

   ┌─────────────────────────────────────────────────────────────────────┐
 ►─▼─┬─ ALL ───────────────────────────────────────────────────────────┬─┴─; ─►◄
     ├─ SYSTEM ────────────────────────────────────────────────────────┤
     ├─ TASK ──────────────────────────────────────────────────────────┤
     │  ┌────────────────────────────────────────────────────────────┐ │
     └──▼── FROM (begin-snap-location) ─┬─ TO (end-snap-location) ─┬─┴─┘
                                        └─ LENGTH (snap-length) ───┘

Parameters

TITLE (title)

Specifies the title to be printed at the beginning of each page of the snap. If requested, a title must contain 134 characters; the first character is reserved for use by the system, and the second character must be a valid ASA carriage control character (blank, 0, 1, +, or -). Title is the symbolic name of a user-defined field that contains the title.

ALL/SYSTEM/TASK

Requests a formatted snap of specified areas.

ALL

Writes a snap of both task and system areas. Areas associated with the issuing task are formatted separately from the system areas. (Task areas are also included with the system areas but are not itemized by task.)

SYSTEM

Writes a snap of system areas.

TASK

Writes a snap of task areas.

FROM (begin-snap-location)

Writes a snap of the specified memory location. Begin-snap-location is the symbolic name of a user-defined field that indicates the starting location of the area to be snapped.

TO (end-snap-location)

Indicates the end of the area to be snapped and is specified following the last data-item to be included in the snap. End-snap-location is the symbolic name of either a user-defined dummy byte field or a field that contains a data item not associated with the area requested in the snap.

LENGTH (snap-length)

Defines the length, in bytes, of the area to be included in the snap. Snap-length is either the symbolic name of a user-defined field that contains the length of the data area, or the length itself expressed as a numeric constant.

Example

The following Example illustrates a SNAP statement that writes a memory snap of the specified memory location:

SNAP TITLE (SNAP_TITLE)
  FROM (START_LOC) TO (END_LOC);

Status Codes

Upon completion of the SNAP function, the ERROR_STATUS field in the system communications block indicates the outcome of the operation:

0000

The request has been serviced successfully.

4032

The derived length of the specified snap storage area is zero or negative.