TLMSMAIN is the root module of CA TLMS. When attached as a subtask by the CTS, TLMSMAIN performs housekeeping functions, and then waits on the completion of one of the following three events:
The following programs are executed by TLMSMAIN:
This message queue processor is called by TLMSMAIN when a transaction has been queued for CA TLMS by the TLMSQMGR SVC. The queue processor invokes the TLMSQMGR SVC to dequeue and retrieve the transaction, then examines the transaction type to determine the appropriate processing path. If a gummed volume label is appropriate to the transaction in process, the label printing routine is invoked here. If the file access process has not concluded successfully, the operator is notified. Finally, if the initiator of the transaction is waiting for completion (for example, the TLMSOPEN routine at OPEN for output time), this module notifies it by post.
TLMSUPDT manages access to the Volume Master File at the logical level. Records are retrieved from the VMF, updated with the data from transaction records passed from TLMSMSGQ, and written back to the file. If the optional ALOG file is indicated, a log record is written (for eventual use if recovery is necessary). File utility functions, such as OPEN and CLOSE, are managed by this module.
Physical access to the Volume Master File is accomplished by routines in program TLMSVMRW, which is called by TLMSUPDT. TLMSVMRW performs the physical function (read, write and so forth) after ensuring serialization of the resource (VMF) using an ENQUEUE/RESERVE technique. When this program is called, the target record is defined by key, such as VSN; this program contains the detailed code necessary to locate the record through the use of control/index arrays and so forth.
Note: For more information about the CTS address space and the subtasks it supports, see the chapter "Common Tape System" in this guide.
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