SWITCH STREAM command

Summary

Privileges

System manager

Function

You can switch streams — parallel, ring, concatenated, GDG — to the next member at any time.

Syntax

SWITCH STREAM streamname [RESET]

Where:

streamname

CCAJRNL, CCAJLOG, CHKPOINT, or CHKPNTS. The command is valid only for these streams.

RESET

This optional parameter causes any disabled parallel GDG members to be reopened during the switch. Valid only when CCAJLOG or CCAJRNL are defined as a parallel stream defined with GDG members, as in the following example, which specifies two complete copies of CCAJLOG using GDGs as a base: DEFINE STREAM CCAJLOG … PARALLEL=(P1,P2) … DEFINE STREAM P1 … GDG=(D1) … DEFINE STREAM P2 … GDG=(D2) … DEFINE DATASET D1…. DEFINE DATASET D2… Note: RESET of CCAJNRL is only possible as version 8.0 of Model 204. A custom zap may be available for earlier versions.

Usage notes

• If you specify:
  • A journal stream (CCAJRNL or CCAJLOG): the currently active data set is closed and the next data set defined to the stream is opened.
  • A checkpoint stream (CHKPOINT or CHKPNTS): the currently active data set in the stream is closed after the next record is written to the data set.
• If a SWITCH STREAM CCAJRNL command is issued during CHECKPOINT EXTENDED QUIESCE command processing, the journal is switched, a new checkpoint is issued, and the duration of the extended quiesce time-out set in CPQZSECS is reset to its maximum, original value (disregarding the already-elapsed time).
• A SWITCH STREAM CCAJRNL RESET command is only allowed during CHECKPOINT EXTENDED QUIESCE command processing. Ie

CHECKPOINT SET E Q CHECKPOINT SWITCH STREAM CCAJRNL RESET CHECKPOINT UNSET E Q

• For an extensive discussion about using the SWITCH STREAM command, see Tracking system activity (CCAJRNL, CCAAUDIT, CCAJLOG).

See also

• DEFINE STREAM command
• COPY STREAM command
• Configuring checkpoint and journal data streams