VSAM linear datasets with Datacom/AD 15.1

Products

• Datacom/AD
• DATACOM - AD
• Datacom
• Datacom/DB
• COMMON SERVICES FOR Z/OS

Issue/Introduction

The new Datacom/AD installation defaults to using VSAM Linear datasets.  Is this part of a move to use Linear VSAM for everything?

What about databases for Datacom/AD using products like ENF?

Resolution

Most Datacom database and system files can now be defined as VSAM Linear Datasets. This is now the recommended file format as it has various benefits over EXCP datasets including the use of persuasive encryption. VSAM Linear datasets use less resources and are faster on average when performing IO.

Benefits of using VSAM Linear datasets include:

• Supports zHPF
• Performs I/O in SRB mode (zIIP enabled I/O)
• Performs encryption/decryption transparently for Pervasive Encryption
• Supports 64-bit address in all control blocks (and reduces the 24-bit memory requirement)
• Supports more than 16 extents per volume (123)
• Supports growing last extent on volume so even more extends

The documentation on VSAM files is in the main Datacom documentation in section VSAM Linear Datasets with Media Manager.
 
The use of VSAM or BDAM/EXCP datasets is transparent to the Datacom/AD using application as the file access is performed by the Datacom/AD code. 
 
There may not be any documentation update yet, but Datacom/AD using product databases like ENF can be defined as VSAM linear datasets.