Configure IIS AppPool Max Memory via PowerShell

Configure-IISAppPoolMaxMemory.ps1

function Configure-IISAppPoolMaxMemory([string]$AppPoolName = "ApplicationPoolDefaults",
    [int]$MaxMem = 20)
{
    [int]$ExitCode = 0
    
    # Ensure WebAdministration module is loaded.
    if ((Get-Module -Name WebAdministration) -eq $null)
    {
        Write-Log "Importing module: WebAdministration"
        Import-Module -Name WebAdministration -ErrorAction SilentlyContinue | Write-Log
        if ((Get-Module -Name WebAdministration) -eq $null)
        {
            Write-Log -IsError "Error: Unable to import module: WebAdministration"
            $ExitCode = 1
            return $ExitCode
        }
    }
    
    # Percentage
    if ($MaxMem -gt 0 -and $MaxMem -lt 100)
    {
        Write-Log "Setting maximum memory to $($MaxMem)% of total system memory."
        $ComputerSystem = Get-WmiObject -Class Win32_ComputerSystem
        $SystemMemMb = [System.Math]::Round($ComputerSystem.TotalPhysicalMemory/(1024*1024))
        Write-Log "System memory: $($SystemMemMb)MB"
        $MaxMemMb = [System.Math]::Floor(($SystemMemMb*$MaxMem)/100)
        Write-Log "Setting maximum memory to $($MaxMemMb)MB."
    }
    # Unlimited
    elseif ($MaxMem -eq 0)
    {
        $MaxMemMb = 0
        Write-Log "Setting maximum memory to 0 (unlimited)."
    }
    # MB value
    else
    {
        $MaxMemMb = $MaxMem
        Write-Log "Setting maximum memory to $($MaxMemMb)MB."
    }
    
    # ApplicationPoolDefaults is a special case
    if ($AppPoolName -eq "ApplicationPoolDefaults")
    {
        $ConfigurationFilter = "/system.applicationHost/applicationPools/applicationPoolDefaults/recycling/periodicRestart"
    }
    else
    {
        $ConfigurationFilter = "/system.applicationHost/applicationPools/add[@name='$AppPoolName']/recycling/periodicRestart"
    }
    
    $Property = Get-WebConfigurationProperty -Filter $ConfigurationFilter -Name "privateMemory"
    if ($Property -ne $null)
    {
        [System.Int64]$CurrentMaxMemKb = $Property.Value
        [System.Int64]$NewMaxMemKb = $MaxMemMb*1024
        if ($CurrentMaxMemKb -ne $NewMaxMemKb)
        {
            Write-Log "Changing Private Memory Limit (KB) configuration property value from $($CurrentMaxMemKb) to $($NewMaxMemKb)."
            Set-WebConfigurationProperty -Filter $ConfigurationFilter -Name "privateMemory" -Value $NewMaxMemKb
        }
        else
        {
            Write-Log "The Private Memory Limit (KB) configuration property is already set to the specified value: $NewMaxMemKb"
        }
    }
    else
    {
        Write-Log -IsError "Unable to find privateMemory configuration property at: $ConfigurationFilter"
        $ExitCode = 2
    }
    
    return $ExitCode
}