In threaded applications, you can code COBOL statements for input and output in QSAM, VSAM, and line-sequential files.
Each file definition (FD) has an implicit serialization lock. This lock is used with automatic serialization logic during the input or output operation that is associated with the execution of the following statements:
Automatic serialization also occurs for the implicit MOVE that is associated with the following statements:
WRITE record-name FROM identifier READ file-name INTO identifier
Automatic serialization is not applied to any statements specified within the following conditional phrases:
related concepts
File-definition (FD) storage