When are IDMS database files allocated/opened?

Products

• IDMS

Issue/Introduction

It has been noticed that some IDMS database files are not allocated at startup. What causes certain files not to be allocated and opened during startup?

Environment

Release: All supported releases.

Cause

A different process occurs for allocating and opening database files depending on the definition in the DMCL of how the area is readied at startup. 

Resolution

1. For areas defined in DMCL to come up in UPDATE mode to CV:
   If the area maps to a single file, the file is allocated and opened during startup and locked for update by CV.
   If the area is mapped to multiple files, the first file is allocated and opened during startup and locked for update by CV. Subsequent files are allocated and opened as pages in those file are accessed by database transactions.
2. For areas defined in DMCL to come up in RETRIEVAL mode to CV:
   The file or files for the area are not allocated/opened at startup. They are only allocated and opened when pages from the area are requested by a database transaction.