Codefile verification validates the integrity of a codefile prior to execution. When a new codefile is created, the MCP generates a checksum for the codefile based on its contents. The MCP can verify this checksum to prevent execution of codefiles that fail verification.
| Note: | Currently, CHECKSUM is the only supported verification method. |
Codefile verification is controlled by the CODEVERIFYCHECK security option, which determines if codefile verification is enabled, and the security option, which specifies that the MCP uses a checksum to verify the codefile. See Controlling System Security for more information on these security options.
When codefile verification is enabled, the following codefile verification data attributes are stored in the disk header:
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SEG0 – The first record of the codefile that includes statistical information about the codefile, including the number of executions and initial stack size.
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Data portion – The remainder of the codefile that includes read-only information, such as the actual code for execution.
