## Virtual Device Driver Reference for OS/2

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### VDHFreezeVDM - Purpose

Context Issues: This function can be called in the task or interrupt context.

DOS Session Terminations: The DOS Session Manager thaws a frozen DOS session prior to calling any VDM_TERMINATE user hooks.

Notes: Each DOS session has a freeze count. This count starts at zero when the DOS session is created. Each VDHFreezeVDM call adds one to this count. Each VDHThawVDM call subtracts one from this count. The DOS session is frozen when the freeze count is 1 (one) or greater. The DOS session is thawed when the freeze count is 0 (zero). This allows multiple virtual device drivers to perform freeze and thaw operations without inadvertently causing the DOS session to run. If this count exceeds MAX_FREEZE_COUNT, VDHFreezeVDM returns VDHERR_FROZEN_LIMIT.