VSAM buffer sizes

The buffer sizes (in bytes) that you can choose when using VSAM as the access method are.

• 512
• 1024
• 2048
• 4096
• 8192
• 12288
• 16384
• 20480
• 24576
• 28672
• 32768

In order not to waste buffer space, choose a buffer size that is the same as a valid CI size. Valid CI sizes for VSAM data clusters are:

• For data components up to 8192 bytes (or 8K bytes), the CI size must be a multiple of 512.
• For data components over 8192 bytes (or 8K bytes), the CI size must be a multiple of 2048 (up to a maximum of 32768 bytes).

Valid CI sizes (in bytes) for VSAM index clusters using VSAM catalogs are:

• 512
• 1024
• 2048
• 4096

Valid CI sizes for VSAM index clusters using integrated catalog facility catalogs are:

• For index components up to 8192 bytes (or 8K bytes), the CI size must be a multiple of 512.
• For index components over 8192 bytes (or 8K bytes), the CI size must be a multiple of 2048 (up to a maximum of 32768 bytes).